Integrated circuit with optical data communication

ABSTRACT

An integrated circuit is configured for optical communication via an optical polymer stack located on top of the integrated circuit. The optical polymer stack may include one or more electro-optic polymer devices including an electro-optic polymer. The electro-optic polymer may include a host polymer and a second order nonlinear chromomophore, the host polymer and the chromophore both including aryl groups configured to interact with one another to provide enhanced thermal and/or temporal stability.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation-in-Part of, and claimspriority benefit from copending U.S. patent application Ser. No.12/246,957, entitled INTEGRATED ELECTRO-OPTIC DEVICE AND METHOD OFMAKING, filed Oct. 7, 2008; which claims priority benefit from U.S.Provisional Patent Application Ser. No. 61/088,782, entitled INTEGRATEDELECTRO-OPTIC DEVICE AND METHOD OF MAKING, filed Aug. 14, 2008; both ofwhich are, to the extent not inconsistent with the disclosure herein,incorporated by reference in their entirety. The present application isalso a Continuation-in-Part of, and claims priority from copending U.S.patent application Ser. No. 12/959,898, entitled STABILIZEDELECTRO-OPTIC MATERIALS AND ELECTRO-OPTIC DEVICES MADE THEREFROM, filedDec. 3, 2010, which is a Continuation-in-Part of, and claims priorityfrom copending U.S. patent application Ser. No. 12/270,714, entitledNONLINEAR OPTICAL CHROMOPHORES WITH STABILIZING SUBSTITUENT ANDELECTRO-OPTIC DEVICES, filed Nov. 13, 2008; which claims prioritybenefit from U.S. Provisional Patent Application Ser. No. 61/003,433,entitled NONLINEAR OPTICAL CHROMOPHORES WITH STABILIZING SUBSTITUENT ANDELECTRO-OPTIC DEVICES, filed Nov. 15, 2007. The present application andcopending U.S. patent application Ser. No. 12/959,898 also claimpriority benefit from U.S. Provisional Patent Application Ser. No.61/315,797, entitled ELECTRO-OPTIC CHROMOPHORE MATERIAL AND DEVICES WITHENHANCED STABILITY, filed Mar. 19, 2010; and which claims prioritybenefit from U.S. Provisional Patent Application Ser. No. 61/383,282,entitled ELECTRO OPTIC CHROMOPHORE AND HOST POLYMER SYSTEM FOR which areincorporated by reference in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The inventions disclosed herein were made with U.S. Government supportpursuant to NRO Contract No. NRO000-07-C-0123 and DARPA Contract No.W31P4Q-08-C-0198. Accordingly, the U.S. Government may have certainrights in the inventions disclosed herein.

BACKGROUND

Integrated circuit (IC) performance can be limited by constraints posedby off-chip communication speed. Electrical interconnections offer onlyrelatively low data rates. Optical communication can be faster, butunfortunately optical interconnections formed using optical devicesembedded in silicon occupy valuable substrate real estate that cannotalso be used for conventional integrated device circuits. What is neededis an optical interconnection approach for integrated circuits thatoffers high bandwidth and minimizes consumption of semiconductor area tothe exclusion of other circuitry.

Moreover, conventional electro-optic modulation materials such aslithium niobate (LiNbO₃) can suffer from requirements for highmodulation voltage and can pose contamination problems if used in asilicon IC fabrication facility. What is needed is an optical materialthat can form active and passive optical devices without posing asubstantial contamination risk to a semiconductor processing facility.What is also needed is an optical material that can be formed to includeactive devices having modulation voltages that are available on aconventional IC. What is also needed is an optical material that can beprocessed under conditions (e.g., temperature) that do not degradeunderlying IC structures.

SUMMARY

According to an embodiment, an integrated circuit (IC) can be formed toinclude an optical polymer stack disposed over at least portions of(superjacent to) the IC. The polymer stack can include at least oneelectro-optic polymer layer that can be poled and configured to form aportion of an electro-optic device. The IC can be configured to modulatean electric field across the poled electro-optic polymer, the electricfield modulation causing the poled electro-optic polymer to undergo anelectro-optic response comprising a modulated index of refraction. Themodulation of the index of refraction causes modulation of the data ontoone or more optical wavelengths of light operatively coupled to theelectro-optic device.

The electro-optic polymer can include a host polymer including an arylgroup and a second order non-linear chromophore having two or moresubstituents that also include aryl groups. The aryl groups of the hostpolymer and the chromophore can interact to reduce the tendency of thechromophore to rotate from its poled position, thus reducing thetendency of the electro-optic polymer to undergo a reduction inelectro-optic response with time and temperature. The host polymer canbe selected to have a relatively high glass transition temperature tofurther stabilize the positions of the chromophore molecules.

According to an embodiment, an integrated circuit configured for opticalcommunication includes an integrated circuit including at least oneconductor layer; and an optical polymer stack disposed on the integratedcircuit and the at least one conductor layer, the optical polymer stackincluding at least one electro-optic core The integrated circuit caninclude circuitry configured to modulate data onto at least one opticalwavelength operatively coupled to the at least one electro-optic coreThe electro-optic core can include a poled electro-optic polymerincluding a host polymer with at least one aryl group and a poledchromophore including two or more aryl substituents configured tosterically interact with the at least one aryl group of the host polymerto hinder rotation of the chromophore after poling.

According to an embodiment, a method for making an integrated circuitwith an optical interface includes providing an integrated circuitincluding a conductive layer including at least one first electrode andforming, over the integrated circuit, at least a portion of an opticalpolymer stack including an electro-optic polymer, the electro-opticpolymer including a host polymer including an aryl group and a secondorder non-linear optical chromophore having one or more arylsubstituents. The aryl substituents of the chromophore and the arylgroup of the host polymer can be selected to interact to stabilize apoled position of the chromophore.

According to an embodiment, an integrated circuit configured for opticalcommunication includes an integrated circuit, an optical polymer stackformed at least partially on the integrated circuit, and an opticaldetector configured to receive a modulated optical signal and convertthe optical signal to a first electrical signal. A circuit module may beformed as a portion of the integrated circuit operatively coupled to theoptical detector receive first data corresponding to the firstelectrical signal and responsively output second data. An electro-opticmodulator including an electro-optic polymer formed at least partiallyin the optical polymer stack, may be operatively coupled to the circuitmodule and configured to modulate light to output a modulated lightsignal corresponding to the second data.

According to an embodiment, an integrated circuit with an opticalinterface includes a semiconductor substrate with a pattern of dopedwells on the surface of the semiconductor substrate and a plurality ofpatterned conductor layers and patterned dielectric layers disposed overthe surface of the semiconductor substrate and forming a circuit layer.An optical polymer forming a planarization layer may be disposed overthe circuit layer.

According to an embodiment, a method for making an integrated circuitconfigured for optical communication includes providing an integratedcircuit including at least one first electrode and forming an opticalpolymer stack over the integrated circuit. Forming the optical polymerstack may include forming at least one electro-optic polymer corelocated over at least a portion of the at least one first electrode.

According to an embodiment, a method for configuring an integratedcircuit for optical communication may include applying a bottom opticalcladding polymer over the surface of an integrated circuit, curing thebottom cladding polymer to form a bottom polymer clad, and etching oneor more features in the bottom polymer clad.

According to an embodiment, a method for making an integrated circuitconfigured for optical communication may include providing an integratedcircuit, applying a bottom polymer optical clad over the integratedcircuit, applying an electro-optic polymer over the bottom polymer clad,and etching one or more features in the electro-optic polymer.

According to an embodiment, a polymer electro-optic device includes,disposed between a high speed electrode and an electro-optic polymer, avelocity-matching layer configured cause an electrical propagationvelocity through the high speed electrode to approximate an opticalpropagation velocity through the electro-optic polymer.

According to an embodiment, a method of making a polymer electro-opticdevice includes forming an electro-optic polymer layer over a substrate,including: forming a velocity-matching layer over the electro-opticpolymer layer, and forming a high speed electrode over thevelocity-matching layer.

According to an embodiment, an electro-optic polymer stack includes afirst polymer layer having a first coefficient of thermal expansiondisposed over an integrated circuit or other substrate having asubstrate coefficient of thermal expansion, and a second polymer layerhaving a second coefficient of thermal expansion, wherein the firstcoefficient of thermal expansion has a value between the substratecoefficient of thermal expansion and the second coefficient of thermalexpansion.

According to an embodiment, an electro-optic polymer stack includes anelectro-optic polymer layer including one or more polar species, and oneor more upper layers disposed over the electro-optic polymer layer,wherein the one or more upper layers include relatively non-polarpolymers configured to substantially prevent water vapor from migratingfrom an environment over the one or more upper layers to theelectro-optic polymer layer.

The summary given above is not meant to be limiting but rather toprovide a convenient overview for the reader. The full scope and meaningwill become apparent in reference to the written description, drawings,and attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a partial side sectional diagram of an integrated circuit(IC) configured for optical communication, according to an embodiment.

FIG. 1B is a partial cross sectional diagram of the IC configured foroptical communication of FIG. 1A, according to an embodiment.

FIG. 2 is a block diagram of an illustrative IC with an optical datainterconnection, according to an embodiment.

FIG. 3 is a flow chart illustrating a method for making an electro-opticpolymer semiconductor integrated circuit, such as those shown in FIGS.1A, 1B, and 2, according to an embodiment.

FIG. 4 is a diagram illustrating a poling configuration used to make anintegrated circuit configured for optical data communication, accordingto an embodiment

FIG. 5 is a side sectional view of a planarized semiconductor integratedcircuit configured to drive a thickened bottom electrode of anelectro-optic device, according to an embodiment.

FIG. 6 is a side sectional view of a planarized semiconductor integratedcircuit configured to drive a bottom electrode of an electro-opticdevice, according to another embodiment.

FIG. 7 is a side sectional view of a planarized semiconductor integratedcircuit configured to drive a bottom electrode of an electro-opticdevice, according to another embodiment.

FIG. 8 is a side sectional view of an electro-optic polymersemiconductor integrated circuit including top and bottom electrodes,according to an embodiment.

FIG. 9 is a sectional diagram of an integrated photodetector configuredto provide a feedback signal to an integrated circuit with an opticaldata interface, according to an embodiment.

FIG. 10 shows illustrative molecular structures of several chromophoresthat can form a portion of an electro-optic polymer and an electro-opticpolymer device used to provide an optical interface for an integratedcircuit, according to embodiments.

FIG. 11 shows a synthesis of an illustrative chromophore, according toan embodiment.

FIG. 12 illustrates the substitution of aryl groups onto anotherchromophore, according to an embodiment.

FIG. 13 illustrates the synthesis of chromophores including bulkysubstituents, according to an embodiment.

FIG. 14 illustrates an electron donor for a chromophore and a syntheticscheme for a chromophore including the donor, according to anembodiment.

FIG. 15 illustrates host polymer molecular structures, according toembodiments.

FIGS. 16A-16F include graphs showing Jonscher analyses of temporalstability of electro-optic polymers, according to embodiments.

FIG. 17 is a graph showing hyperbolic tangent model analyses of temporalstability of illustrative electro-optic polymers, according toembodiments.

FIG. 18 is a graph showing Jonscher analysis of temporal stability ofillustrative electro-optic polymers, according to embodiments.

FIG. 19 illustrates fabrication steps for an electro-optic polymermodulator, according to an embodiment.

FIG. 20 is a conceptual view of a Mach-Zehnder interferometer andelectrodes, according to embodiments.

FIG. 21 is a photomicrograph showing a cross section of a fabricatedoptical polymer stack taken across an electro-optic modulator, accordingto an embodiment.

FIG. 22A is a graph showing a Jonscher analysis of temporal stability ofan electro-optic polymer modulator spanning 3000 hours, according to anembodiment.

FIG. 22B is a graph showing a Jonscher analysis showing projected longterm temporal stability of an electro-optic polymer modulator spanning25 years, according to an embodiment.

FIG. 23 is a diagram illustrating pi-interactions between a host polymerincluding aryl groups and an aryl substituent on a chromophore,according to an embodiment.

FIG. 24A is a diagram illustrating pi-electron interactions betweenparallel aryl groups of a host polymer and a substituent of achromophore, according to an embodiment.

FIG. 24B is a diagram illustrating pi-electron interactions betweenorthogonal aryl groups of a host polymer and a substituent of achromophore, according to an embodiment.

FIG. 24C is a diagram illustrating additional pi-electron interactionsbetween parallel aryl groups of a host polymer and a substituent of achromophore, according to an embodiment.

FIG. 24D is a diagram illustrating pi-electron interactions betweenparallel and orthogonal aryl groups of a host polymer and a substituentof a chromophore, according to an embodiment.

FIG. 25 is a block diagram illustrating an integrated circuit configuredfor optical communication, according to another embodiment.

FIG. 26 is a sectional view of an integrated circuit configured foroptical communication showing a bottom clad layer configured to provideplanarization and a velocity-matching layer, according to otherembodiments.

FIG. 27A is a diagram illustrative of a surface adhesion treatment,according to an embodiment.

FIG. 27B is a diagram illustrative of another surface adhesiontreatment, according to an embodiment.

FIG. 28 is a flowchart showing a method for making an integrated circuitconfigured for optical communication, according to an embodiment.

FIG. 29 is a sectional view of an optical stack structure including acoupling between a horizontal waveguide and a z-axis launch to or from acomponent formed at the surface of an IC, according to an embodiment.

FIG. 30 is a sectional view of another optical stack structure includinga coupling between a horizontal waveguide and a z-axis launch to or froma top-mounted component, according to an embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description and drawings are not meant to be limiting. Otherembodiments may be utilized, and other changes may be made, withoutdeparting from the spirit or scope of the subject matter presented here.

Referring to FIGS. 1A and 1B, according to embodiments, an integratedcircuit (IC) 101 may be generally formed to include a semiconductorlayer 102 including doped regions 104, a circuit layer 105 of patternedconductors 106 and insulation 107 over the semiconductor layer 102, andan optical layer 110 of patterned optical polymer materials (andoptionally one or more electrodes 116) over the circuit layer 105.Various barrier layers, adhesion promotion layers, passivation layers,etc. (not shown) may also be included in the semiconductor 102, circuit105, optical polymer stack 110 making up the IC 101. Generally, opticalcomponents in the optical polymer stack are larger in scale thanintegrated circuit components. For clarity purposes, in figures herein,integrated circuit conductors 106, insulation 107, and doped regions 104are shown significantly expanded in scale compared to optical polymercomponents. Moreover vertical scale can be expanded compared tohorizontal scale.

Referring to FIG. 2A, viewing the IC 101 from above, the IC 101 caninclude a die 205 supporting a plurality of electrical circuit sections203 configured to perform conventional processing, memory, logic,switching, communication, etc. functions; and can include one or moreactive and/or passive optical devices 120 disposed over the conventionalcircuit sections. Actuation or modulation electrodes 136 a, 136 b, 136c, 136 d, 136 d′ can be formed from one or more patterned conductors 106included in the circuit layer 105. As may be appreciated frominspection, ICs made according to embodiments can include conventionalcircuit sections 203 across substantially the entirety of a die 205, andoptical communications devices superposed over and above theconventional circuit sections 203.

According to embodiments, a relatively low voltage semiconductorintegrated circuit may be configured to drive an electro-optic polymermodulator at a corresponding voltage without additional amplification.

A semiconductor integrated circuit may include a number patterned metallayers. Typically, memory ICs may include about four patterned metallayers, and microprocessors may include about eleven patterned metallayers, for example. A planarization layer may be formed over the topmetal layer, and bottom cladding, electro-optic core, and top claddingmay be formed over the planarization layer to form an integratedelectro-optic device. Optionally, a smooth bottom electrode may beformed over the planarization layer and below the bottom cladding. Aplurality of such devices may be disposed on a singulated die. Anintegrated circuit with an optical interconnection may include one ormore signal multiplexers, one or more modulator drivers operativelycoupled to the one or more signal multiplexers, and one or moreelectro-optic modulators operatively coupled to the one or moremodulator drivers. The integrated circuit with an opticalinterconnection may include at least one light phase bias device and mayinclude a calibration circuit configured to provide an indication ofelectro-optic response to an external system. The integrated circuitwith an optical interconnection may include a feedback circuitconfigured to at least partially control the light phase bias device.

FIGS. 1A and 1B are respective side sectional and cross-sectional viewsof an integrated circuit configured for optical communication 101,according to an embodiment. A semiconductor substrate 102 includes atleast one doping layer 104 patterned across the semiconductor substrateto form portions of semiconductor devices. At least one conductor layer106 is patterned over the semiconductor substrate. A planarization layer108 can be disposed at least partly coplanar with and over the at leastone conductor layer 106. A optical polymer stack 110 can be disposedover the planarization layer 108. According to an alternativeembodiment, the planarization layer 108 can be omitted, and theplanarization function can be provided by a portion of the opticalpolymer stack 110.

At least one via 112 may at least partially extend through the opticalpolymer stack 110. The at least one via may be operatively coupled to acorresponding location on the at least one patterned conductor layer106. A top conductor layer 114 is disposed over the optical polymerstack and in electrical continuity with the at least one via 112. Unlesscontext dictates otherwise, the term “top conductor”, as used herein,refers to a conductor formed on the top of the optical polymer stack110.

As an alternative to a via 112, other conductors may be substituted toelectrically couple the top conductor layer to at least one location onthe at least one patterned conductor layer 106. For example, the atleast one conductor may be formed entirely or in combination from a via,a wire bond, a conductive bump, and/or an anisotropic conductive region.

The top conductor layer 114 may be formed to include a metal layer or aconductive polymer, for example. The top conductor may be plated toincrease its thickness. The top conductor layer may include at least onehigh speed electrode 116 formed as a pattern in the top conductor layer114, the high speed electrode 116 being operatively coupled to receive asignal from the at least one via 112 or other conductive structure fromthe corresponding location on the at least one patterned conductor layer106. Thus, the at least one via 112 or other conductive structure isconfigured to transmit an electrical signal from semiconductorelectrical circuitry formed on the semiconductor substrate 102 to the atleast one high speed electrode 116 through or around the optical polymerstack 110.

According to embodiments, the at least one patterned conductor layer 106is configured to form a ground electrode 118 parallel to the at leastone high speed electrode 116. An active region 120 of the opticalpolymer stack 110 is positioned to receive a modulation signal from thehigh speed electrode 116 and the ground electrode 118. The active region120 includes an electro-optic composition formed as a poled region thatcontains at least one second order nonlinear optical chromophore.Chromophores and electro-optic compositions are described more fullybelow.

The optical polymer stack 110 is configured to support the active region120. The optical polymer stack 110 can also include passive waveguidestructures. For example, a polymer waveguide can receive and guide light122 to and from the active region and/or to and from the vicinity of theactive region. The optical polymer stack 110 may include at least onebottom cladding layer 124 and at least one top cladding layer 126disposed respectively below and above an electro-optic layer 128. Thebottom 124 and top 126 cladding layers, optionally in cooperation withan optional planarization layer 108, are configured to guide insertedlight 122 along the plane of the electro-optic layer 128. Light guidingstructures 130 are formed in the optical polymer stack 110 to guide thelight 122 along one or more light propagation paths through theelectro-optic layer 128 and/or non-active core structures (not shown).In the embodiment of FIGS. 1A and 1B, the guidance structures 130 areformed as trench waveguides that include etched paths in the at leastone bottom cladding layer 124.

Second order non-linear optical chromophores are generally formed asmolecules having a structure D-π-A, where D is an electron donorstructure, A is an electron acceptor structure having a relativelyhigher electron affinity than the electron donor structure D, and π is api-orbital conjugated bridge that freely permits electron flow betweenthe donor D and the acceptor A. Such molecules may also be referred toas hyperpolarizable organic chromophores. The molecules are generallylinear and nominally polar due to the difference in electron affinitiesbetween the donor D and acceptor A. Such molecules may be poled intoalignment by applying an electrical poling field during manufacture,with the acceptor A portions being drawn toward a positive potential andthe donor D portions being drawn toward a negative potential. Themolecules may then be locked into the desired alignment by cross-linkingor freezing a polymer matrix in which the chromophores are embedded. Forexample, poling can occur near a glass transition temperature Tg of acomposition including a host polymer and chromophores. Alternatively,the chromophores may be covalently bound or otherwise substantiallyfixed in their poled positions.

Chromophores and corresponding electro-optic compositions that providehigh thermal and/or temporal stability can be advantageous with respectto processing constraints, yield, service temperature constraints,reliability, and service life. Approaches for improving thermal andtemporal stability are described more fully below. Other properties thatcontribute to a successful integration of the optical polymer stack withthe IC include good adhesion to metal, oxide, and semiconductor portionsof the IC surface, sufficient elasticity to compress or stretchcorresponding to thermal expansion of the IC and IC portions, lowoptical loss, and high electro-optic activity. Such considerations canbe satisfied by material systems described herein.

After poling, an electrical modulation field may be imposed through thevolume of chromophores. For example, if a relatively negative potentialis applied at the negative end and a relatively positive potentialapplied at the positive end of the poled chromophores, the chromophoreswill at least partially become non-polar. If a relatively positivepotential is applied at the negative end and a relatively negativepotential is applied at the positive end, then the chromophores willtemporarily hyperpolarize in response to the applied modulation field.Generally, organic chromophores respond very quickly to electricalpulses that form the electrical modulation field and also return quicklyto their former polarity when a pulse is removed.

A region of poled second order non-linear optical chromophores generallypossesses a variable index of refraction to light. The refractive indexis a function of the degree of polarization of the molecules. Thus,light that passes through an active region will propagate with onevelocity in a first modulation state and another velocity in a secondmodulation state. This property, along with the fast response time and arelatively high sensitivity to changes in electric field state makesecond order non-linear optical chromophores excellent bases from whichto construct very high speed optical modulators, phase shifters,micro-ring resonators, variable Bragg grating reflectors, etc.

The IC 101 includes a semiconductor electrical circuit formed from acomplex of the doping layer pattern 104 and the at least one patternedconductor 106 in the circuit layer 115. Typically, ICs include greaterthan one patterned conductor layer. For example, memory circuits may usefour or five conductor layers separated by dielectric layers, andmicroprocessors may use eleven or twelve conductor layers separated bydielectric layers. According to an embodiment, circuitry of the IC canbe configured, when in operation, to drive the electrodes 116, 118 witha series of modulated electrical pulses. A resultant modulatedelectrical field is thus imposed across the active region 120 andresults in modulated hyperpolarization of the poled chromophoresembedded therein. A complex of electrodes 116, 118, active region 120and light guidance structures 130 can be designated as an opticaldevice. The modulated hyperpolarization may thus modulate the velocitylight passed through the poled active region 120 of the optical polymerstack 110. Repeatedly modulating the velocity of the transmitted lightcreates a phase-modulated light signal emerging from the active region.Such an active region 120 may be combined with light splitters,combiners (not shown), and other active regions to create lightamplitude modulators, such as in the form of a Mach-Zehnder opticalmodulator. Another arrangement of an optical device can include an inputlight guide, an optional output light guide, and a ring resonator formedas a poled chromophore active region arranged for wavelength-selectiveevanescent coupling to the input light guide and optionally to theoutput light guide.

A combination of at least one electro-optic active region 120, at leasttwo electrodes 116, 118, and corresponding light guiding structures 124,126, 130 may be considered an electro-optic device 132, 134. Atwo-channel electro-optic device 134 may be formed from one groundelectrode 118 and corresponding pairs of active regions 120 and highspeed electrodes 116 a, 116 b. The two channels of a two channelelectro-optic device 134 may operate in cooperation, such as in apush-pull manner to form a Mach Zehnder optical modulator.

Additional devices may be formed using electrodes or resistors 136 thatare not configured for high speed operation. The operation of one suchillustrated device is described below in conjunction with thedescription of an optical phase bias device.

FIG. 2 is a diagram of an illustrative IC configured for opticalcommunication 201, according to an embodiment. The IC 201 of FIG. 2 can,for example, be configured as an integrated electro-optic modulatorcircuit. The IC 201 includes a driver circuit 202 including at least oneamplifier 204 formed from a complex of doped semiconductor regions 104and the patterned at least one conductor layer 106 showndiagrammatically in FIGS. 1A and 1B. The driver circuit 202 is operableto amplify a multiplexed signal to produce a series of relatively lowvoltage modulated electrical pulses. The modulated electrical pulses areconducted to two high speed electrodes 116 a, 116 b disposed overcorresponding active regions 120 shown diagrammatically in FIGS. 1A and1B and a combined ground electrode 118.

The illustrative IC 201 includes a push-pull Mach Zehnder modulator 134.Accordingly, an output stage 204 of the driver circuit 202 includes anoutput 206 that drives a D+ node and a complementary output 208 that ismodulated inversely from the output 206 to drive a D− node. The output206 and complementary output 208 are each conducted to a correspondinghigh speed electrode 116 a, 116 b. Each high speed electrode 116 a, 116b is thus driven by an electrical signal that is the inverse of theelectrical signal delivered to the other high speed electrode 116 b, 116a. The driver circuit 202 may be further configured to drive the groundelectrode 118 to a desired voltage. While the term “ground” is usedgenerically, and in some cases may equal actual chip ground, a differentpotential or set of potentials may alternatively be used to form theground potential.

According to an alternative embodiment, the output stage 204 of thedriver circuit 202 includes an output 206 that drives a single node. Theoutput 206 is conducted to a corresponding high speed electrode 116. Thehigh speed electrode 116 is thus driven by an electrical signal thatmodulates a single channel active region 120. Such an alternativeembodiment may form a single channel phase modulator.

According to another alternative embodiment, two output stages may besynchronized (with or without phase offset or inversion), each outputstage including an output that drives a single node. Since the outputstages are synchronized, they may be used to cooperatively driverespective electro-optic channels, for example as complementarychannels, as phase-delayed channels, or in another relationship. Theseparate synchronized output channels may alternatively be used to drivea single electro-optic modulation channel, for example by combiningtheir outputs in a cascade, by inputting signals at separate signalinjection points, or by using one node to drive a signal at the frontend of the high speed electrode and using another node to drive acorresponding signal at the back end of the high speed electrode (e.g.,in a bipolar drive arrangement). Especially in the latter configuration,signal matching circuitry (described below) may be omitted, the functionthereof being provided by the back end drive signal.

The driver circuit 202 can receive the multiplexed signal through a nodeD from a multiplexer circuit 210 that is also formed from a complex ofdoped semiconductor regions 104 and the patterned at least one conductorlayer 106 shown diagrammatically in FIGS. 1A and 1B. The multiplexercircuit 210 is operable to multiplex a plurality of input signalsreceived at nodes D1, D2, D3, and D4 to produce the multiplexed signalat node D. The nodes D1, D2, D3, and D4 may be operatively coupled to aplurality of package leads for receiving corresponding data signals froma system (not shown) to which the IC 201 is connected.

According to an embodiment, the multiplexer circuit 210 can include anN×M multiplexer. For example, N may be 2, 4, 8, 16, or 32. M may be afrequency such as 2.5 GHz, 10 GHz, 25 GHz, 40 GHz or 100 GHz. Accordingto an embodiment, the multiplexer circuit 210 is a 4×2.5 Gbpsmultiplexer that produces a 10 Gbps multiplexed signal at node D.

The illustrative integrated circuit 201 can also include integratedmatching circuitry 212 a, 212 b configured to receive pulses from therespective high speed electrodes 116 a, 116 b and substantially preventreflections. The matching circuitry 212 a, 212 b may be formed at leastpartially from a patterned region of the top conductive layer and may becoupled to the high speed electrodes 116 a, 116 b at locations selectedto tune their frequency response to a desired bandwidth. The matchingcircuitry may include a plurality of connections to each of the highspeed electrodes 116 a, 116 b. The matching circuitry may be furtherformed at least partially from a complex of patterned at least onedoping layer 104 and patterned at least one conductor layer 106 showndiagrammatically in FIGS. 1A and 1B. Thus, the high speed electrodes areable to support traveling electrical pulses that enter at the left endand propagate left-to-right along their length. Accordingly, highbandwidth pulses may form a traveling waveform that is substantiallysynchronized with the velocity of light traveling through the activeregions.

While processing of optical polymers and second order non-linear opticalchromophores may generally be quite repeatable, variations in ambienttemperature, processing, material, or fabrication tolerances may createvariations in the response of a given optical device or portion of anoptical device formed in part by the active region. Such variations inresponse may be compensated for by providing a phase bias structureand/or by selecting a modulation voltage, phase, duty cycle, etc.

The integrated polymer electro-optic semiconductor circuit 201 mayinclude a calibration storage circuit 214. The calibration storagecircuit 214 is configured to store at least one calibration valuecorresponding to a response of the electro-optic circuit to a signalimposed from a system (not shown) to which the integrated electro opticsemiconductor circuit 201 is coupled. The calibration storage circuit214 includes at least one node C1, C2, C3, C4, C5, C6, C7, C8 216corresponding to a package lead coupled to the calibration value, thepackage lead configured to provide the calibration value to the system.

The calibration storage circuit 214 may be formed from an array offusable links or non-volatile storage memory such as flash, ROM, maskROM, PROM, EPROM, EEROM, or other memory technology compatible with theprocessing technology used to form the semiconductor portion of theintegrated circuit 201. Alternatively, the calibration storage circuitmay be formed in the package but on a structure separate from thesemiconductor substrate, and may use a memory technology not necessarilycompatible with the integrated circuit 201.

The integrated polymer electro-optic semiconductor circuit 201 mayfurther include at least one second region of the optical polymer stackpositioned proximate to a bias resistor 136, also shown in FIG. 1A. Anunpoled region of the electro-optic layer 128 including at least onesecond order non-linear optical chromophore may form a portion of athermo-optic bias device 218 configured to uniformly phase shift a phasemodulated light signal transmitted therethrough. The bias device 218 isresponsive to a voltage difference between bias signals Vc, Va receivedfrom the system (not shown) (or alternatively, as described below, froma voltage source driven by an integrated feedback circuit) and deliveredto the bias resistor 136. The bias signals Vc, Va may be used to heatthe region of the electro-optic layer 128 to produce a relatively stablephase offset to a light signal delivered through one of the activeregions 120 to produce phase-matched modulated light signals. Accordingto embodiments, the bias resistor 136 is driven to dissipate less thanabout 10 to 50 microwatts.

The optical bias device 218 can be used to tune the optical output tonormally low or normally high at no pulse, may be used create zerocrossings at desired points in the pulses, and/or may be used tocompensate for device-to-device variations in response.

While the description of FIG. 2 presented heretofore has focusedprimarily on the electrical portions of the circuitry, opticalstructures are also present in the IC 201, as described above. Opticaltransmission paths are shown in long-short dashed lines to make themeasier to see relative to the electrical portions of the circuit.

A coherent light signal 122 enters an input waveguide 220. Typically,the light 122 may be provided by a laser, such as an infrared fiberlaser and/or distributed feedback laser (not shown) that may be locatedoff chip. The light from an off-chip laser can be coupled to the inputwaveguide 220 using an optical coupler 221. Optionally, light can belaunched into the input waveguide 220 from an integrated laser such as avertical cavity stimulated light emission (VCSL) laser or a chip lasermounted on the top of the optical polymer stack 110. Light receivedalong an orthogonal axis such as above or below a planar waveguide canbe launched into the waveguide by a mirror formed in the optical polymerstack 110.

Light proceeds along the input waveguide 220, guided as described above,and is then split into two components by a splitter 222. From there, thetwo components propagate to the active regions as described above. Thecomplementary driver circuit 202 drives one electrode 116 a to increasein voltage and the other electrode 116 b to decrease in voltagecorresponding to the multiplexed data signal. Thus, light propagatesfaster along one active region of the two channel device 134 than theother region of the two channel device. The two phase-shifted channelsare then recombined at a combiner 224. Because the input light iscoherent, it may constructively interfere if the phase differencebetween the two channels corresponding respectively to electrodes 116 aand 116 b is substantially zero or a multiple of 2π radians offset.Alternatively, the combined light may destructively interfere at thecombiner 224 if the phase difference between the channels is other than2π radians phase offset, and may reach a maximum modulation depth,including up to substantial extinction, at odd multiples of π offset.Thus, the complementary pulses with which the electrodes 116 a and 116 bdrive the two optical channels may be converted from complementaryoptical phase modulation to optical amplitude modulation. After thelight channels are combined, the modulated light propagates out along anoutput waveguide 226, which may be coupled to other optical devicesand/or be transmitted off-chip through an output fiber coupler 221.

The (minimum) voltage at which maximum modulation depth occurs in adevice may be referred to as Vπ. Depending on context, Vπ may refer to avoltage magnitude applied to each of two push-pull electrodes or avoltage applied to a single modulation channel. Second order non-linearoptical chromophore-based electro-optic devices generally have anadvantage over prior art electro-optic devices with respect to operatingwith a smaller Vπ. In particular, second order nonlinear opticalchromophore-based electro-optic devices may be configured to reachacceptable modulation depths when driven at a Vπ as low as voltages thatmay be directly output by relatively low voltage semiconductor devices,including CMOS devices. Acceptable performance of non-linearchromophore-based push-pull Mach-Zehnder modulators has been achieved ata drive voltage of less than 2 volts, making such materials and devicescompatible with conventional on-chip semiconductor voltages.

Material (cladding, host polymer, chromophore) chemistry, properties,and interactions are important for achieving acceptable performance,service life, environmental range, and compatibility with semiconductor,metal, and oxide surfaces. Particular materials that meet knownapplication needs including low voltage modulation compatible withintegration over a conventional integrated circuit are described indetail below.

Optionally, an integrated feedback circuit 228 may be configured tomeasure the modulated light output signal delivered to the outputwaveguide 226. The feedback circuit 228 may determine the bias voltageVc and/or Va that drive the bias resistor 136.

For example, the feedback circuit 228 may include a coupling waveguide230 configured to evanescently receive a small portion of the outputsignal from the output waveguide 226. The thus tapped light signal maybe converted to an electrical signal by a photodetector 232. Ananalog-to-digital converter 234, which for example may be formed fromone or more comparator circuits, may be sampled by an embeddedmicrocontroller 236 at one or more frequencies selected to determine adepth of modulation.

For example a short range modulated light signal may have a desiredmodulation depth of about 5 dB or more. A long range modulated lightsignal may have a desired modulation depth of about 20 dB or more. Themicrocontroller 236 may be operatively coupled to control the gain of anamplifier or attenuator 238 that drives the bias voltage across the biasresistor 136. Additionally or alternatively, the microcontroller 236 maybe operatively coupled to control the gain of the driver circuit 202.

FIG. 3 is a flow chart illustrating a method 301 for making anelectro-optic polymer semiconductor integrated circuit, such asembodiments shown in FIGS. 1A, 1B, and 2, for example, according to anembodiment.

In step 302, an integrated semiconductor electrical circuit may beformed, for example by using conventional MOS, NMOS, PMOS, or CMOS toform an integrated semiconductor circuit 102. Alternatively, thesemiconductor integrated electrical circuit may be fabricated orpurchased in the form of a partially or fully processed semiconductorwafer. For electro-optic modulator technologies such as lithium niobatethat require higher modulation voltages than the approximate 2 volts orless required by an electro-optic chromophore modulator, othersemiconductor technologies that output higher voltages, such as MOS orBiCMOS, may be used to form the semiconductor integrated circuit 102.Optionally, other semiconductor technologies such as III-IVsemiconductors may be used to form the semiconductor integrated circuit.

As described above, the semiconductor integrated circuit may include oneor more doped semiconductor junctions configured to provide a signal toor receive a signal from the at least one electrode. For example, adoped semiconductor junction may form an output transistor configured todrive the at least one electrode. For example, the at least oneelectrode may be toggled relative to a ground electrode that is laterformed above the optical polymer stack or may maintain the at least oneelectrode at a selected voltage relative to a toggled electrode that islater formed above the optical polymer stack.

Proceeding to step 304, the surface of the integrated semiconductorcircuit can be planarized. The planarization layer may be formed from avariety of transparent or opaque materials. According to an embodiment,the planarization layer may be formed from a heat-reflow material, suchas phosphorous- or boron-doped silicon dioxide for example. Theplanarization layer may additionally or alternatively be mechanicallyplanarized, etched to a planar configuration, be chemical mechanicalplanarized (CMP), etc. According to an embodiment, the planarizationlayer may be formed from a material such as a sol-gel, OSG, etc. In someembodiments, it may be desirable to select a planarization material thatis relatively transparent and non-scattering to a wavelength of lightthat is propagated through the optical polymer stack. Forming theplanarization may include spinning, spraying, or otherwise applying theplanarization material, followed by grinding, polishing, etching, CMP,and/or heat reflowing to planarize.

Optionally, planarization may be provided by application of the bottomclad. In such cases, step 304 can be omitted.

According to an embodiment, planarization produces a surface with aroughness of about 10 nanometers root-mean-average (RMA) or less and aflatness less than or equal to about ±10 microns total thicknessvariation (TTV).

Proceeding to step 306, a bottom electrode can be formed. The bottomelectrode formation step 306 may include etching and filling one or morevias through a planarization layer and/or an insulator layer to one ormore conductive pads. The surface of IC can be sputtered, for examplewith gold or aluminum, and etched to form a patterned seed layer. Thepatterned seed layer can then be plated to a desired thickness.According to an embodiment, the bottom electrode is planar to about 10nanometers RMA to minimize optical loss. Alternatively, the bottomelectrode can be allowed to be non-planar, and losses can be minimizedby planarization provided by the bottom clad.

Optionally, at least one IC conductive layer, such as an upper metallayer, can be plated. This may be used to increase the thickness of theat least one electrode and thereby increase its current carryingcapacity.

Steps 302, 304 and 306 result in providing a semiconductor integratedcircuit including a plurality of ground electrodes operatively coupledto a plurality of semiconductor junctions. One or more of the steps 302,304, and 306 may be carried out at a facility that also performsadditional steps described below. Alternatively, the semiconductorintegrated circuit may be provided by purchasing the circuit from asupply partner.

Proceeding to step 308, the integrated circuit, for example in the formof a processed silicon wafer, has at least a portion of an opticalpolymer stack applied. At least a portion of the optical polymer stackincludes forming at least a bottom cladding layer over the planarizedsemiconductor integrated circuit, and forming an electro-optic polymerlayer including second order non-linear chromophores over the bottomcladding layer.

The bottom cladding layer can include, for example, a polymer, anelectro-optic polymer with a lower refractive index than theelectro-optic polymer layer, an organic-inorganic hybrid, an inorganicmaterial, or a combination thereof.

Additionally, step 308 can include fabricating additional light guidingstructures. In some embodiments, the light guiding structure includes anoptical waveguide in the form of a trench, a side clad, a channel, arib, a quasi trench, or a quasi rib. A top cladding layer and a pollingelectrode may be formed over the electro-optic layer.

Proceeding to step 310, at least portions of the second order non-linearoptical chromophores in the electro-optic polymer adjacent theelectrodes are poled and cured to substantially fix the alignment of thechromophores in the electro-optic polymer layer in their poledorientation.

A poling apparatus may include a poling electrode that is held incontact with the surface of the partial optical polymer stack, or acorona discharge mechanism such as a high voltage grid above the surfacein which charges are introduced to the surface through ionization of agas. Typically, in either approach, poling is performed under asubstantially inert gas such as helium, nitrogen, or argon. The entiresemiconductor wafer or at least the electro-optic polymer layer is curedwhile the poling voltage is maintained. For example, the assembly may beraised to a temperature of approximately 140 degrees C. while a polingvoltage of about 400 to 1100 volts is held across the electro-opticpolymer layer. According to some embodiments, the poling voltage may beabout 600-1000 volts, and more specifically between 750 and 950 volts.The temperature and poling voltage may be maintained for about 1-2minutes, the voltage holding the poled orientation of the chromophoremolecules while a host polymer is cross-linked to “trap” thechromophores in their poled orientation. Alternatively, a UV or otherradiation cured host polymer may be used and curing may includeapplication of cross-linking radiation instead of or in addition to theapplication of heat. Alternatively, the chromophores themselves mayinclude cross-linking portions and the chromophores may covalently bondto a host polymer and/or to one another to maintain orientation.Alternatively, the host polymer may be fully linked, and curing caninclude simply lowering the temperature to below the glass transitiontemperature, T_(g), of the electro-optic polymer.

In some embodiments, the poling electrode may be wider than a trench,rib, quasi trench, or quasi rib guiding structure so that the electricfield generated between the poling electrode and ground electrode iswider than the waveguide. For the rib or quasi rib forms, a top claddinglayer or portion of a top cladding layer may be thicker in areasadjacent to the waveguide than in the area between the waveguide andpoling electrode. In another embodiment, the electro-optic polymer layerincludes a quasi trench and the polymer stack further includes a firstpolymer side clad and a second polymer side clad adjacent to the quasitrench and overlying the bottom clad layer.

Typically, the poling temperature is within ±15° C. of the glasstransition temperature (Tg) of the electro-optic polymer layer; but thepoling temperature may be another temperature at which the chromophoresare mobile enough for alignment at a given poling field voltage. Furthermaintenance of the poling temperature may be sufficient to inducecuring. Alternatively, the temperature may be raised or lowered to allowcuring to progress.

Proceeding to step 312, the remainder of the optical polymer stack isapplied and cured. This step may include stripping a poling electrode,if used, prior to applying one or more additional layers. The polingelectrode may be removed, for example, by wet etching, dry etching, or acombination thereof. After the poling electrode is removed, the surfacemay be treated with, for example, plasma, adhesion agents, solvents, orany combination thereof to improve surface quality and adhesion of theupper cladding layer.

A polymer top cladding layer is formed over the electro-optic polymerlayer. Depositing the upper cladding layer (or other layer) may include,for example, spin deposition, dip coating, screen printing, evaporation,chemical vapor deposition, sputtering, vacuum deposition, etc. In someembodiments, the top cladding layer is formed from photo-cross-linkableepoxies or a photo-cross-linkable acrylates.

Proceeding to step 314, a plurality of conductive vias are formedthrough the polymer bottom clad layer, the electro-optic polymer layer,and the polymer top clad layer. For example, such vias may be formed byetching the cured materials and filling the etched voids with aconductive material. The conductive material may include a vacuumdeposited metal such as gold or aluminum, or a conductive polymer.Optionally, the etched holes may be lined with an insulating materialsuch as an insulating polymer or other material prior to filling with aconductive material. Alternatively, conductive vias may not be formedand instead gold wirebonds or other structure may be formed tooperatively couple portions of the semiconductor circuit to the topelectrodes.

Proceeding to step 316, top electrodes are formed. For example topelectrodes may include high speed strip electrodes. Alternatively,ground electrodes may be formed on top of the optical polymer stack andthe electrodes formed from the at least one semiconductor integratedcircuit metal layer may be configured as high speed electrodes.

In optional step 318, the top electrodes may be plated. Plating may beused to increase the current carrying capacity of the top electrodes,and may be especially useful when the top electrode is configured to bevoltage toggled.

After the top electrodes are formed (and optionally plated), the process301 proceeds to optional step 320. In step 320, at least one performanceparameter of at least one optical modulation channel is characterized.An optical modulation channel is formed by a corresponding group of aground electrode, high speed electrode, and poled electro-optic polymerportion. As described in part above, the relative phase, frequencyresponse, extinction ratio, optical loss, and/or other aspects ofperformance of an electro-optic device may vary according to variationsin chemistry, the fabrication process, design, manufacturing equipmentor other effects. To provide a relatively uniform response from part topart, it may be desirable to provide to a host system an indication ofone or more performance parameters. If, for example, a given device isdetermined to have somewhat higher optical loss than nominal (but belowallowable limits), a system may provide a higher output illuminationsource into the device to compensate for the higher loss. In anotherexample, if a given amplitude modulation device is found to havesomewhat less that complete extinction of light at a nominal off state,then the Vπ modulation voltage may be increased somewhat to achieve morecomplete extinction (destructive interference) of the light.

In step 320 (which may optionally occur after singulation and/or devicepackaging) device performance is characterized by measuring a response.According to an example, optical probes may be inserted into the opticalpolymer stack at locations correlated to a light input location and alight output location. The device may be operated, for example using abed of nails or other probe, to modulate light received from the testapparatus. An optical signal received at the output optical probe may bemeasured, compared to nominal values, and a calibration valuedetermined. The calibration value may directly represent a measuredresponse, or alternatively may be a value that corresponds to theresponse in a known way. According to an embodiment, one or moreresponse aspects may be measured, combined, and the combined value usedto access a look-up-table (LUT) to determine a calibration value.

Proceeding to step 322, the calibration value (or a data valuecorresponding to the calibration value) may be recorded on theintegrated circuit for future reference by a system. Optionally, thecalibration value may be stored and later written to the integratedcircuit after packaging.

Proceeding to step 324, the integrated circuit is packaged to includeone or more optical couplers 221 and a plurality of package leadsoperatively coupled respectively to optical and electrical nodes on thedie. As mentioned above, the optical performance of the integratedcircuit may optionally be characterized and the calibration data writtenafter packaging.

Optionally, for embodiments where characterization 320 is performed atthe wafer level, if the optical polymer stack is found to be detective,the wafer may be reworked, as indicated at 326. Reworking may includeetching to remove the detective polymer stack and then repeatingprocessing to form the optical polymer stack.

FIG. 4 is a sectional diagram illustrating a poling configuration 401used to make an integrated circuit configured for optical communication,according to an embodiment. As shown in FIG. 4, a bottom electrode 118may be provided electrical continuity with a poling pad 402. The polingpad 402 may be disposed near the bottom electrode 118. Alternatively,the poling pad 402 may be disposed some distance from the bottomelectrode 118. According to an embodiment, a poling pad 402 may beprovided electrical continuity with a plurality of bottom electrodes118. Optionally, a poling pad 402 may be configured to have electricalcontinuity with a plurality of bottom electrodes 118 when the assemblyis in wafer form, and then the continuity may be broken (and optionallythe poling pad discarded), when the integrated dice are singulated.

The embodiment of FIG. 4 also illustrates an alternative placement ofthe bottom electrode 118. For comparison, FIGS. 1A-1B illustrates abottom electrode 118 that is formed at least partly from the topmostmetallization layer disposed on the semiconductor integrated circuit102. In comparison, the bottom electrode 118 of FIG. 4 is formed over aplanarization layer 108. The configuration of FIG. 4 may be preferablein some embodiments for maintaining bottom electrode flatness.

With reference to FIG. 4, a contact electrode 404 may be placed toprovide a first potential at an upper surface of the optical polymerstack 110. In the example shown, an upper poling electrode 405 is formedover at least a portion of the optical polymer stack 110, and aremovable contact electrode 404 is placed in contact with the upperelectrode 405. The contact electrode 404 may drive the upper electrode405 or the surface of the at least partial optical polymer stack at afirst poling potential.

A second removable contact electrode 406 may pierce or otherwise passthrough the optical polymer stack 110 to make electrical contact withthe poling pad 402. Since the poling pad 402 is in electrical continuitywith the lower electrode 118, a second poling potential imposed by thesecond removable contact electrode 406 is communicated to the lowerelectrode 118. Accordingly, a poling voltage is provided across theelectro-optic active region disposed between the upper 405 and lower 118electrodes. While the first and second poling potentials provide apoling voltage to at least a portion of an active electro-opticchromophore region disposed proximate the electrodes, the electro-opticactive region 120 and other uncured portions of the optical polymerstack 110 may be cured as described above.

The top poling electrode 405 formed at the surface of the opticalpolymer stack prior to applying the poling potential may include atemporary top poling electrode that is in place during poling. In suchan embodiment, the top poling electrode 405 may be subsequently removedfrom the surface of the optical polymer stack after poling and curingthe electro-optic polymer, according to procedures described above.Alternatively, poling may be performed after substantially the entireoptical polymer stack 110 is formed. In such embodiments, the upperpoling electrode may be an upper electrode 116, 136 that remains withand is configured to modulate the device.

As an alternative to the configuration of FIG. 4, a conductive via maybe formed to couple to the poling pad 402 and electrical contact made tothe conductive via during poling. The poling pad 402 is configured toreceive the poling voltage, either through a penetrating poling probe406, through a conductive via (not shown), or by scraping the polymerstack 110 to expose the poling pad 402. Generally, the poling pad 402 isonly exposed to a source of the poling voltage during a manufacturingprocess. The poling pad 402 and/or the upper poling electrode 405 may beremoved after poling. In operation, the lower electrode 118 may beconfigured to receive a modulation voltage from a driver circuit portion408 and the upper electrode 116 may be configured to receive amodulation voltage from a second driver circuit portion 410. To protectthe semiconductor integrated circuit portions 408, 410 from dielectricbreakdown damage during poling, the poling electrode 405, which iselectrically isolated from semiconductor circuitry, typically receives apoling voltage while the poling pad, and hence the bottom electrode, isheld at ground. Subsequent to poling, a conductive via 412 may be formedto form a conductive path between the top high speed electrode (notshown) and a conductive pad 414.

FIGS. 5, 6 and 7 illustrate embodiments for forming bottom electrodesthat include semiconductor metallization layers in the circuit layer 105

FIG. 5 is a partial side sectional diagram of an integrated circuitconfigured for optical communication 501, according to an embodiment.

A semiconductor integrated circuit 102 includes a semiconductorsubstrate with at least one conductor layer 106 formed at or near itstop surface. Semiconductor devices 502, 504 may be formed in regions ofa patterned doped layer at the surface of the semiconductor substrate,such as by methods including p and n doping, etc. The conductor layer106 may be formed as a single conductor layer, for example.Alternatively, the conductor layer 104 may include one or more of aplurality of conductor layers 506, 508, 510.

According to an embodiment, a portion of the conductor layer 106 may beformed by successively forming a first layer of conductive material 512and then a second layer of conductive material 514 one above the other.Such successively formed layers may be made such that the successivelayers are substantially in direct contact with one another, such aswith no intervening material or with only a relatively thin adhesionlayer formed therebetween.

FIG. 6 is a side sectional view of a planarized semiconductor integratedcircuit 601 configured to drive a bottom electrode of an electro-opticdevice, according to another embodiment.

The conductor layer 106 may include an upper layer 512 of a plurality ofconductor layers 106. An upper conductive layer 512 may be formed overone or more similarly shaped lower (e.g. “buried”) conductor layers 508,but with one or more layers of insulating material 602 disposedtherebetween.

FIG. 6 is a side sectional view of a planarized semiconductor integratedcircuit configured to drive a bottom electrode of an electro-opticdevice, according to another embodiment.

FIG. 7 is a side sectional view of a planarized semiconductor integratedcircuit 701 configured to drive a bottom electrode of an electro-opticdevice, according to another embodiment.

Alternatively, the at least one conductor layer 106 may include an upperconductor layer 512 may be held in electrical continuity with one ormore lower conductor layers 508, such as by forming and filling aplurality of conductive vias 702 a, 702 b, 702 c, 702 d, and 702 ethrough one or more insulating layers 602 between the respectiveconductive layers 512, 508.

At least portions of the one or more conductive layers 106 may, forexample, be formed to include a metal such as aluminum, copper, gold,and/or silver and alloys thereof. The one or more conductive layers 106may additionally or alternatively be formed from a semiconductormaterial such as doped polysilicon.

Referring to FIG. 5, the conductive layer 106 may include a firstportion 512 formed according to a photolithographically defined processsuch as CVD, etc. and a second portion 514 formed by electroplating thefirst portion. Accordingly, the actual and/or effective thickness of theconductive layer 106 may vary rather significantly, according to variousembodiments. Additionally or alternatively, the conductive layer 106 maycorrespond to a conductive channel formed in the semiconductor substrateitself.

Referring to FIGS. 1A and 1B, one or more conductive layers 106 may beformed to provide separated structures 118, 138 as described above. Suchseparated structures 118, 138 may for example be formed as separatedelectrodes including, for example, ground electrodes or high speed stripelectrodes. While the one or more conductive layers 106 is shown asbeing formed as separated structures 118, 138, alternatively the one ormore conductive layers 106 may be formed as a substantially continuousstructure, such as a ground electrode, for example.

FIG. 8 is a side sectional view of an electro-optic polymersemiconductor integrated circuit 801 including upper and bottomelectrodes 116, 118, respectively, according to an embodiment. The upperelectrode 116 may be formed from two layers 802 and 804 and may bedriven by a semiconductor integrated device including a doped region 104through a conductive via 112 as shown.

The optical polymer stack 110 may include one or more bottom claddinglayers 124, a waveguide core 128, and one or more top cladding layers126. Typically the refractive indices of the one or more bottom claddinglayers 124, waveguide core 128, and one or more top cladding layers 126are selected to guide at least one wavelength of light along the core.For example, the top and bottom clad layers 126, 124 may be selectedhave an index of refraction of about 1.35 to 1.60 and the waveguide core128 may be selected to have a nominal index of refraction of about 1.57to 1.9. According to one illustrative embodiment, the top and bottomclad layers 126, 124 have an index of refraction of about 1.50 and thewaveguide core 128 has an index of refraction of about 1.74. The atleast one wavelength of light may include light in the C or L band atabout 1510 to 1620 nanometers wavelength. According to one embodiment,the light is at about 1550 nanometers wavelength. According toembodiments, the one or more bottom clad, side clad, and/or one or moretop clad layers may include materials such as polymers (e.g.,crosslinkable acrylates or epoxies or electro-optic polymers with alower refractive index than electro-optic polymer layer),inorganic-organic hybrids (e.g., “sol-gels”), and inorganic materials(e.g., SiOx).

According to an embodiment, at least a portion of the waveguide core 128includes an electro-optic polymer core. For example, the electro-opticpolymer core 120 may include poled electro-optic chromophores whoseindex of refraction is variable as a function of electric field strengthpassed therethrough. (Optionally, one or more portions of the bottomand/or top clad layers 124, 126 may also include electro-opticmaterial.)

The electro-optic polymer may be, for example, a guest-host system, aside chain polymer, a crosslinkable system, or a combination thereof.Various taper and butted structures may form borders betweennon-electro-optic and electro-optic portions of the optical polymerwaveguide core 128.

According to an embodiment, the voltage of the upper electrode 116 maybe toggled and the voltage of the lower electrode 118 may be maintainedat a relatively constant (e.g. ground) potential to produce themodulated electrical field across the electro-optic portion(s) 120 ofthe waveguide core 128. According to another embodiment, the voltage ofthe upper electrode 116 may be maintained at a relatively constant (e.g.ground) potential and the voltage of the lower electrode 118 may betoggled. According to another embodiment, the voltage of both the upperelectrode(s) 116 and the lower electrode(s) 118 may be toggled, forexample in opposing directions. When both electrodes 116 and 118 aretoggled, the magnitude of respective voltage swings may be balancedaccording to the current carrying capacity of the respective conductivelayers, for example with a greater voltage toggle being impressed upon athicker conductor structure.

According to an embodiment, an electrical propagation velocity throughone or more electrodes 116, 118 may be approximately matched to anoptical propagation velocity through the light guiding structures 130and the electro-optic core 120. For example, referring to FIG. 1A, anelectrode 118 formed in the conductor layer 106 may receive anelectrical pulse at its left end, with the electrical pulse thentraveling left-to-right along the electrode 118 while light energy 122also travels left-to-right through the electro-optic core 120.Similarly, an electrode 116 may receive an electrical pulse at its leftend, the electrical pulse then traveling left-to-right along its length,parallel to light 122 travel through the electro-optic core 120. Suchelectrode structures may be referred to as strip electrodes. Suchvelocity matching between the electrical and optical signals may provideenhanced modulation bandwidth, cleaner modulated signals, etc. comparedto alternative electrode structures.

Referring to FIG. 1B, a two optical channel device 134 such as a MachZehnder modulator, a single optical channel device 132 such as a phasemodulator or other combinations may be formed according to variousembodiments. A plurality of devices may be formed on a given die.

While the light guiding structures 130, aka waveguides, are shown asbeing formed using a trench waveguide approach, other waveguidestructures may be used. For example a quasi-trench, rib, quasi-rib, sideclad, etc. may be used singly or in combination to provide light guidingfunctionality.

FIG. 9 illustrates an approach for forming the feedback photodetector232 of FIG. 2, according to an embodiment. Tapped light 902 is receivedthrough the feedback waveguide 230 formed between the bottom and topcladding layers 124, 126. A scattering region 904 is formed to scatterthe received tapped light 902. The scattering region may, for example,be loaded with a scattering agent such as titanium dioxide.Alternatively, the scattering region 904 may include one or morescattering faces etched into the waveguide 230 and configured topartially reflect, refract, or diffract the received light. At least aportion of the received light is launched downward where it is receivedand converted into an electrical signal by an integrated siliconphotodetector 904. The integrated photodetector 904 may, for example,include a silicon photodiode.

Alternatively, the bottom of the output waveguide 226 (FIG. 2) orunderlying bottom cladding layer 124 may be partially etched orotherwise modified to scatter a portion of the modulated output lighttravelling along the output waveguide 226 to impinge upon the integratedphotodiode 904.

The photodetector 904 may be formed to include a photodiode, aphotoresistor, or phototransistor. Alternatively, a photodetector may becoupled to the top surface of the optical polymer stack 104 andelectrically coupled to the analog-to-digital converter 234 of FIG. 2.Alternatively, the photodetector 232 may include integratedanalog-to-digital conversion circuitry, and a separate analog-to-digitalconverter may be omitted.

The chemistry, and resultant physical, optical, and electricalproperties, of the optical polymer stack 110 can be important forachieving desired performance. Written description of preferred opticalpolymer compositions is provided next.

Optical Polymer Composition

According to embodiments, hyperpolarizable chromophores used in devicesdescribed herein may include second order nonlinear optical chromophoreshaving the structure D-π-A, wherein D is a donor, π is a π-bridge, and Ais an acceptor, and wherein at least one of D, π, or A is covalentlyattached to a substituent group including a substituent center that isdirectly bonded to at least two aryl groups, preferably three arylgroups. What is meant by terms such as donor, π-bridge, and acceptor;and general synthetic methods for forming D-π-A chromophores are knownin the art, see for example U.S. Pat. No. 6,716,995, incorporated byreference herein.

A donor (represented in chemical structures by “D” or “D^(n)” where n isan integer) includes an atom or group of atoms that has a low oxidationpotential, wherein the atom or group of atoms can donate electrons to anacceptor “A” through a π-bridge. The donor (D) has a lower electronaffinity that does the acceptor (A), so that, at least in the absence ofan external electric field, the chromophore is generally polarized, withrelatively less electron density on the donor (D). Typically, a donorgroup contains at least one heteroatom that has a lone pair of electronscapable of being in conjugation with the p-orbitals of an atom directlyattached to the heteroatom such that a resonance structure can be drawnthat moves the lone pair of electrons into a bond with the p-orbital ofthe atom directly attached to the heteroatom to formally increase themultiplicity of the bond between the heteroatom and the atom directlyattached to the heteroatom (i.e., a single bond is formally converted todouble bond, or a double bond is formally converted to a triple bond) sothat the heteroatom gains formal positive charge. The p-orbitals of theatom directly attached to the heteroatom may be vacant or part of amultiple bond to another atom other than the heteroatom. The heteroatommay be a substituent of an atom that has pi bonds or may be in aheterocyclic ring. Exemplary donor groups include but are not limited toR₂N— and, R_(n)X¹—, where R is alkyl, aryl or heteroaryl, X¹ is O, S, P,Se, or Te, and n is 1 or 2. The total number of heteroatoms and carbonsin a donor group may be about 30, and the donor group may be substitutedfurther with alkyl, aryl, or heteroaryl. The “donor” and “acceptor”terminology is well known and understood in the art. See, e.g., U.S.Pat. Nos. 5,670,091, 5,679,763, and 6,090,332.

An acceptor (represented in chemical structures by “A” or “A^(n)” wheren is an integer) is an atom or group of atoms that has a low reductionpotential, wherein the atom or group of atoms can accept electrons froma donor through a π-bridge. The acceptor (A) has a higher electronaffinity that does the donor (D), so that, at least in the absence of anexternal electric field, the chromophore is generally polarized, withrelatively more electron density on the acceptor (D). Typically, anacceptor group contains at least one electronegative heteroatom that ispart of a pi bond (a double or triple bond) such that a resonancestructure can be drawn that moves the electron pair of the pi bond tothe heteroatom and concomitantly decreases the multiplicity of the pibond (i.e., a double bond is formally converted to single bond or atriple bond is formally converted to a double bond) so that theheteroatom gains formal negative charge. The heteroatom may be part of aheterocyclic ring. Exemplary acceptor groups include but are not limitedto —NO₂, —CN, —CHO, COR, CO₂R, —PO(OR)₃, —SOR, —SO₂, and —SO₃R where Ris alkyl, aryl, or heteroaryl. The total number of heteroatoms andcarbons in a acceptor group is about 30, and the acceptor group may besubstituted further with alkyl, aryl, and/or heteroaryl. The “donor” and“acceptor” terminology is well known and understood in the art. See,e.g., U.S. Pat. Nos. 5,670,091, 5,679,763, and 6,090,332.

A “π-bridge” or “electronically conjugated bridge” (represented inchemical structures by “π” or “π^(n)” where n is an integer) includes anatom or group of atoms through which electrons may be delocalized froman electron donor (defined above) to an electron acceptor (definedabove) through the orbitals of atoms in the bridge. Such groups are verywell known in the art. Typically, the orbitals will be p-orbitals ondouble (sp²) or triple (sp) bonded carbon atoms such as those found inalkenes, alkynes, neutral or charged aromatic rings, and neutral orcharged heteroaromatic ring systems. Additionally, the orbitals may bep-orbitals on atoms such as boron or nitrogen. Additionally, theorbitals may be p, d or f organometallic orbitals or hybridorganometallic orbitals. The atoms of the bridge that contain theorbitals through which the electrons are delocalized are referred tohere as the “critical atoms.” The number of critical atoms in a bridgemay be a number from 1 to about 30. The critical atoms may besubstituted with an organic or inorganic group. The substituent may beselected with a view to improving the solubility of the chromophore in apolymer matrix, to enhancing the stability of the chromophore, or forother purpose.

The substituent group (or any of multiple substituent groups) may becovalently attached to one or more of D, π, and A through a variety oflinkages including single bonds, single atoms, heteroatoms, metal atoms(e.g., organometallics), aliphatic chains, aryl rings, functionalgroups, or combinations thereof. The substituent center may havemultiple atoms (e.g., an aryl or aliphatic ring), may be a single atom(e.g., a carbon, silicon, or metal atom), or may be a combinationthereof (e.g., a ring system where one aryl group is bonded to one atomof the ring system and the other two aryl groups are bonded to anotheratom in the ring system).

For example, in some embodiments the substituent center includes acarbon atom, a heteroatom, or a metal atom. In other embodiments, thesubstituent center may be a carbon atom, a silicon atom, a tin atom, asulfur atom, a nitrogen atom, or a phosphorous atom. In an embodiment,the substituent center may be a 3-, 4-, 5-, or 6-membered ring like abenzene ring, thiophene ring, furan ring, pyridine ring, imidazole ring,pyrrole ring, thiazole ring, oxazole ring, pyrazole ring, isothiazolering, isooxazole ring, or triazole ring.

The aryl groups bonded to the substituent center may be furthersubstituted with alkyl groups, heteroatoms, aryl groups, or acombination thereof. For example, in some embodiments, the aryl groupsmay, independently at each position, comprise a phenyl ring, a naphthylring, a biphenyl group, a pyridyl ring, a bipyridyl group, thiophenegroup, furan group, imidazole group, pyrrole group, thiazole group,oxazole group, pyrazole group, isothiazole group, isooxazole group,triazole group or an anthracenyl group.

In an embodiment, the substituent group includes the structure:

-   -   wherein: X is the substituent center; Ar¹, Ar², and Ar³ are the        aryl groups; and L is a covalent linker attached to D, π, or A.        According to various embodiments, X may be C, Si, N, Sn, S,        S(O), SO₂, P(O), aromatic ring, or P; Ar¹, Ar², and Ar³ each        independently include a substituted or un-substituted phenyl        ring, a substituted or un-substituted benzyl ring, a substituted        or un-substituted naphthyl ring, a substituted or un-substituted        biphenyl group, a substituted or un-substituted pyridyl ring, a        substituted or un-substituted bipyridyl group, a substituted or        un-substituted thiophene ring, a substituted or un-substituted        benzothiophenene ring, a substituted or un-substituted imidazole        ring, a substituted or un-substituted thiozale ring, substituted        or un-substituted thienothiophene group, substituted or        un-substituted a substituted or un-substituted quinoline group,        or a substituted or un-substituted anthracenyl group; and L        includes the structure:

-   -   wherein: R¹ is independently at each occurrence an H, an alkyl        group, or a halogen; Y¹ is —C(R¹)₂—, O, S, —N(R¹)—, —N(R¹)C(O)—,        —C(O)₂—, —C₆H₆—, or —OC₆H₆—, thiophenyl; n is 0-6; and m is 1-3.

Donors, acceptors, and π-bridge moieties may include functional groupsthat may be covalently bonded to the L group.

According to embodiments, D includes:

-   -   π includes:

and

-   -   A includes:

-   -   wherein: R¹, independently at each occurrence is H, an aliphatic        group such as an alkyl or alkoxyl group, or an aryl group. R²,        independently at each occurrence, is an alkyl group, a        halogenated alkyl group, a halogenated aryl group, or an aryl        group with or without substitutions; Z is a single bond,        —CH═CH—, —C≡C—, —N═N—, or —N═CH—; Y², independently at each        occurrence, is CH₂, O, S, N(R¹), Si(R¹), S(O), SO₂, —CH(R¹)— or        —C(R¹)₂—; R³ independently at each occurrence is a cyano group,        a nitro group, an ester group, or a halogen; and at least one        R¹, R², or R³ includes the substituent group. m is 1-6 and n is        1-4.

In another embodiment, D has one of the structures:

wherein X is a substituent center; Ar¹, Ar², Ar³, Ar⁴, Ar⁵, and Ar⁶ arearyl groups; Ar⁷ is a conjugated aromatic group; R¹ of D independentlyat each occurrence is H, an alkyl group, a heteroalkyl group, an arylgroup, or a hetero aryl group; p is 2-6; l is 0-2; m is 1-3; and n is1-3; π includes:

-   -   and A is:

-   -   wherein: R¹ is independently at each occurrence an H, an alkyl        group, or a halogen; Z is a single bond or —CH═CH—; Y² is O, S,        —C(R¹)₂—; R² is independently at each occurrence an alkyl group        or an aryl group; and m=1-3. In embodiments, the nonlinear        optical chromophore includes one of the structures shown in FIG.        10 wherein X, R¹, and R² may be as described above.

According to an embodiment, a nonlinear optical chromophore has thestructure D-π-A, wherein D is a donor, π is a π-bridge, and A is anacceptor; and wherein at least one of D, π, or A is covalently attachedto a substituent group including at least one of:

-   -   and wherein: X is C or Si; Y¹ is —C(R¹)₂—, O, S, —N(R¹)—,        —N(R¹)C(O)—, —C(O)₂—; Y³ is N or P; and Ar¹, Ar², and Ar³ are        aryl groups. The aryl groups, D, π, and A may be, as described        above for example.

Other embodiments include electro-optic composites and polymersincluding one or more of the nonlinear optical chromophores describedabove. Typically, the polymer is poled with an electric field to induceelectro-optic activity. Other techniques such as self-organization orphoto-induced poling may also be used. The nonlinear optical chromophoremay be covalently attached to the polymer matrix (e.g., as in aside-chain polymer or a crosslinked polymer) or may be present as aguest in a polymer matrix host (e.g., a composite material). Thenonlinear chromophore may also be present as guest in the polymer matrixand then be covalently bonded or crosslinked to the matrix before,during, or after poling. Polymers that may be used as a matrix include,for example, polycarbonates, poly(arylene ether)s, polysulfones,polyimides, polyesters, polyacrylates, and copolymers thereof.

In some embodiments, bulky groups on the chromophore are used to changethe Tg and to reduce the optical loss of electro-optic (EO) polymers bychanging the physical interaction between polymer host and chromophoreguest. We found that the physical interaction between host polymer andguest molecular can be increased by selecting specific chemicalstructure of the isolating (e.g., bulky) group on the chromophore.Physical interactions may include, for example, pi-pi interactions, sizeinteractions that block chromophore movement significantly below Tg(e.g., there is not enough free volume in the polymer composite at Tgfor translation of the bulky group, and hence the chromophore, which isgenerally required for chromophore relaxation), and preorganized bindinginteractions where the bulky groups fit preferentially intoconformationally defined spaces in the polymer, or any combinationthereof. In some embodiment, the physical interactions are controlled orsupplemented by van der Waals forces (e.g., Keesom, Debye, or Londonforces) among the moiety of the bulky groups and aryl groups on polymerchains. Such non-covalent interactions may increase temporal stabilitybelow Tg and decrease optical loss while improving chromophore loadingdensity and avoiding the deleterious effects of crosslinking on thedegree of poling-induced alignment.

Pi-pi interactions are known in the art and may include interaction, forexample, between a pi-system and another pi-system (e.g., an aromatic, aheteroaromatic, an alkene, an alkyne, or carbonyl function), a partiallycharged atoms or groups of atoms (e.g., —H in a polar bond, —F), or afully charged atom or groups of atoms (e.g., —NR(H)₃ ⁺, —BR(H)₃ ⁻).pi-interaction may increase affinity of the chromophore guest for thepolymer host and increase energy barriers to chromophore movement, whichis generally required for chromophore relaxation and depoling. In someembodiments, pi-interactions may be used to raise the Tg of a polymer(e.g., by increasing interactions between polymer chains) or the Tg of apolymer composite (e.g., by increasing interactions between the polymerhost and the chromophore guest). In some embodiments, thepi-interactions of the bulky groups increase the Tg of the polymercomposite compared to when pi-interacting moieties on the bulky groupsare replaced with moieties that have no or weak pi-interactions. In someembodiments, pi-interacting groups on the chromophore are chosen tointeract preferentially with pi-interacting groups on the polymer chain.Such preferential interactions may include, for example, pi-interactingdonors/acceptors on the bulky group with complementary pi-interactingacceptors/donors of the polymer chain, or spatial face-to-face and/oredge-to-face interactions between pi-interacting groups on thechromophores and polymer chains, or any combination thereof. In someembodiments, multiple interactions such as a face-to-face andface-to-edge between one or multiple moieties on the chromophore bulkygroup with multiple or one moieties on the polymer chain may increaseinteraction strength and temporal stability. The pi-interactions betweenthe aryl bulky group/s on the chromophore and the aryl groups on thepolymer may be enhanced by complementary geometric dispositions of thearyl groups that enhance the pi interactions (e.g., aryl groupstetrahedrally disposed around a substituent center in the chromophorebulky group may favorably pi-interact (e.g., stack) more efficientlywith aryl groups tetrahedrally disposed around a carbon in the polymerbackbone as shown in a top view (FIG. 23A) and the side view (FIG. 23B),with partial pi-interactions shown) from rotating 90° around thex-axis). In other embodiments, the polymer may be chosen because thechain adopts certain conformations and spatial distributions (e.g.,preorganization) of pi-interacting groups that favor face-to-face (FIG.24A) or face-to-edge (FIG. 24B) interactions with the pi-interactinggroups on the chromophore. Some embodiments may have multipleface-to-face interactions between pi-interacting groups on the polymerand the chromophore (e.g., FIG. 24C) or a combination of face-to-faceand face-to-edge pi-interactions (e.g., FIG. 24D). In other embodiments,pi-interacting donors generally have electron rich p-systems or orbitalsand pi-interacting acceptors generally have electron poor p-systems ororbitals. In some embodiments, the bulky groups on the chromophore havepi-interacting donors or pi-interacting acceptors that are complimentaryto pi-interacting acceptors or pi-interacting donors on the polymerchain. In some embodiments, such pi-interacting acceptors may include,for example, heterocycles such as pyridines, pyrazines, oxadiazoles,etc, and pi-interacting donors may include, for example, heterocyclessuch as thiophene, furan, carbazole, etc. The pi-interactingdonors/acceptors may also include aryl groups that are electronrich/poor from electron donating/withdrawing substituents. In someembodiments, the bulky group includes at least one pi-interactingacceptor complementary to a pi-interacting donor on the polymer chain.In some embodiments, the bulky group includes at least onepi-interacting donor complementary to a pi-interacting acceptor on thepolymer chain.

In some embodiments, the size of the bulky groups preventstranslation/depoling of the chromophore in the polymer free volumesignificantly (e.g., 20° C.) below the Tg of the composite. In someembodiments, the bulky group is substantially 3-dimensional (e.g., thebulky group has bulk-forming moieties tetrahedrally or trigonalbipyramidally disposed around a substituent center atom rather thanhaving a substantially planar or linear arrangement of the bulk-formingmoieties around the substituent center atom). Such 3-dimensionality mayreduce the possibility of the bulky group, and hence the chromophore,form translating through free volume compared to a planar or linearbulky group. The bulk-forming groups may independently comprise, forexample, and an organic moiety having 5 or more carbon atoms. In someembodiments, the bulk-forming groups may independently compriseconformationally rigidified structures such as rings. The rings may bealiphatic, aromatic, or any combination thereof. In some embodiments,the bulk-forming groups may independently comprise aryl groups(aromatics, polycyclic aromatics, substituted aromatics,heteroaromatics, polycyclic heteroaromatics, and substitutedheteroaromatics.

In other embodiments, the bulky groups fit preferentially intoconformationally/spatially defined areas (e.g., pockets) of the polymer.Such areas may be referred to as preorganized for interaction with thebulky groups. Such preorganization may result from the polymer backboneadopting a predetermined conformation or from groups (e.g., pendantgroups) of the polymer adopting predetermined conformation. In someembodiments, the preorganized area of the polymer may havepi-interacting groups, pi-interacting atoms, shape-interacting groups,H-bonding groups, etc that are spatially disposed to preferentiallyinteract with complementary moieties on the bulky group. Theinteractions of the preorganized area on the polymer and the bulky groupmay comprise any interaction described above or any multiplecombinations thereof. In some embodiments, preorganization providesadditional stability compared to just the stabilizing interaction alone.For example, one part of the preorganized pocket may pi-interact with api-interacting moiety on the bulky group and another part of thepreorganized pocket may interact with the same or different moiety ofthe bulky group with van der Waals forces.

In other embodiments, the chromophore may comprise more than one bulkygroup. In some embodiments, the chromophore has at least one bulky groupon the donor and at least one bulky group on the p-bridge or acceptor.More than one bulky group on different parts of the chromophore mayincrease interactions with the polymer backbone and make translation anddepoling more difficult.

Compatibility and stability of composites comprising chromophores havingbulky groups with various host polymers were studied, including the EOproperties. Low optical loss is achieved due to good compatibility,which also is proven by a clean, single Tg transition. EO coefficientswith various host polymers are characterized and their thermal stabilityis monitored at different temperatures. Meanwhile, modulators werefabricated out of those EO composites and their stability is furtherconfirmed.

Some embodiments have a chromophore structure that comprises bulkygroups. Such chromophores show good compatibility with host polymers andlead to high glass transition temperature. Examples of two chromophoresare shown in FIGS. 10-13. Guest-host systems were studied using thesechromophores with various host polymers with different glass transitiontemperature. Host polymers such as 28, 29, and 30 in FIG. 15 belong topolycarbonate family with low to high Tg. In some embodiments, high Tgof the host polymers will lead to higher Tg of the EO composites withthe same chromophore.

According to embodiments, EO composites having high Tg (>120° C.) may befabricated by using a host polymer with a glass transitiontemperature>120° C. In other embodiments, EO composites having high Tg(>120° C.) may be fabricated by using a host polymer with a glasstransition temperature>120° C. and a chromophore with a melting point orTg>120° C. For example, an EO composite including chromophore 23b (FIG.13) in 28 (Tg=286° C.) to have a composite Tg of 167° C. Similarly,results showed an EO composite including 23b chromophore in host polymer29 (Tg=165° C.) to have a composite Tg of 193° C. Both systems showedimproved stability for long term applications having a maximum servicetemperature of 85° C. Chromophore 23a has similar improved stability(Tables 1 and 2 below). In another embodiment, an electro-opticcomposite comprises greater than 35% loading by weight of a chromophorein a host polymer, wherein the Tg of the composite is higher than themelting point, or Tg, of the chromophore itself. In some embodiments,the chromophore loading by weight is at least 45% and the Tg of thecomposite is greater than 150° C. In another embodiment, the hostpolymer may be a semi-crystalline polymer with a low Tg that, when mixedwith a chromophore, forms an amorphous composite with high Tg. In someembodiments, noncovalent interactions between bulky groups on thechromophore and moieties of the semi-crystalline host polymer increasethe Tg of the amorphous composite.

According to embodiments, other host polymers with Tg higher than 150°C. may be used in combination with chromophores having bulky groups toproduce composite EO materials having high Tg, and therefore hightemperature stability over short and/or long terms. Illustrative high Tghost polymers may be formed from the following polymeric systems and/ortheir combinations: polysulfones; polyesters; polycarbonates;polyimides; polyimideesters; polyarylethers; poly(methacrylic acidesters); poly(ether ketones); polybenzothiazoles; polybenzoxazoles;polybenzobisthiazoles; polybenzobisoxazoles; poly(aryl oxide)s;polyetherimides; polyfluorenes; polyarylenevinylenes; polyquinolines,polyvinylcarbazole; and their copolymers.

According to an embodiment, an electro-optic polymer includes anonlinear optical chromophore having the structure D-π-A, wherein D is adonor, π is a π-bridge, A is an acceptor, and at least one of D, π, or Ais covalently attached to a substituent group including a substituentcenter X that is directly bonded to an aryl group, and wherein theelectro-optic polymer has greater temporal stability than when an alkylgroup is substituted for the aryl group. The electro-optic polymer maybe a side-chain, crosslinked, dendrimeric, or composite material.According to an embodiment, the substituent center X is bonded to atleast three aryl groups, and the electro-optic polymer has greatertemporal stability than when alkyl groups independently are substitutedfor the aryl groups. According to an embodiment, the electro-opticcomposite has greater than 80% temporal stability at 85° C. after 100hours.

Other embodiments include various methods for making electro-opticcomposites, and devices therefrom, where the electro-optic compositeincludes a chromophore as described above. According to an embodiment, amethod includes: a) providing a polymer including a nonlinear opticalchromophore having the structure D-π-A, wherein D is a donor, π is aπ-bridge, A is an acceptor, and at least one of D, π, or A is covalentlyattached to a substituent group including a substituent center that isdirectly bonded to an aryl group; and b) poling the polymer to form andelectro-optic polymer, wherein the electro-optic polymer has greatertemporal stability than when an alkyl group is substituted for the arylgroup.

Typically, an aryl group is sterically larger than an alkyl group.Typically, the polymer may be provided as a film by, for example, spindeposition, dip coating, or screen printing. The thin film may also bemodified into device structures by, for example, dry etching, laserablation, and photochemical bleaching. Alternatively, the polymer may beprovided by, for example, molding or hot embossing a polymer melt. Thepoling may include, for example, contact or corona poling. In anothermethod embodiment, the substituent center is bonded to or substitutedwith at least three aryl groups, and the electro-optic polymer hasgreater temporal stability than when alkyl groups independently aresubstituted for the aryl groups.

In some embodiments, the polymer is a composite. In some methodembodiments, the aryl group is sterically larger than the alkyl group.In another method embodiment, the polymer has a T_(g); the T_(g) of thepolymer is within approximately 5° C. compared to when an alkyl group issubstituted for the aryl group, and the temporal stability of thepolymer is greater compared to when an alkyl group is substituted forthe aryl group.

Another embodiment is an electro-optic polymer comprising a nonlinearoptical chromophore comprising the donor (24, FIG. 14):

wherein R¹ independently comprises and alkyl, heteroalkyl, aryl, orheteroaryl group; R² independently at each occurrence comprises an H,alkyl group, heteroalkyl group, aryl group, or heteroaryl group; R³independently at each occurrence comprises a halogen, an alkyl group,and heteroalkyl group, an aryl group, or a heteroaryl group; and n is0-3. Chromophores according to this embodiment may be prepared, forexample, according to the general scheme 25 to 27 shown in FIG. 14.Chromophore according to this embodiment have good nonlinearity due tothe strong donating group and can be derivatized with a number offunctional groups at the —R¹ position. In one embodiment, —R¹ comprisesa bulky group that interactions with the polymer host and the π-bridgeincludes a bulky group that interacts with the polymer host.

Other embodiments are electro-optic devices including the nonlinearoptical chromophores, electro-optic composites, and electro-opticpolymers as described above. The devices may include planar waveguides,free standing thin films, single and multi-mode optical waveguides, andother polymers that are passive (e.g., clad polymers such as acrylates).The devices may also have polymers having combinations of any one of thechromophores and/or with other nonlinear optical chromophores.Additionally, a particular device may have two or more differentcomposites and/or polymers including any one of the chromophores above(e.g., a electro-optic waveguide core polymer having one chromophorewith a relatively high refractive index and a clad polymer having eitherthe same chromophore in less concentration or a different chromophore sothat the refractive index of the clad is lower). In some embodiments,the electro-optic device includes a Mach-Zehnder interferometer, aMichelson interferometer, a micro-ring resonator, or a directionalcoupler.

EXAMPLES

The following synthetic example refers to FIG. 11.

Compound 2:

To compound 1 (10.00 grams) in dioxane (50 ml) in ice bath was addedt-BuOK (1M, 55 ml) and Methyl thioglycolate (5.279 grams). The reactantswere heated to 80° C. for 2 hours and then to 120° C. for 30 min. Then,most of dioxane was distilled off. 1-Bromobutane (20 ml) and DMSO (80ml) was added. The reaction was heated to 150° C. for 2 hours. After thereaction was cooled to room temperature, acetic acid in ice water wasused to acidify the reaction. The product was extracted withdichloromethane. The dichloromethane layer was separated, dried overMgSO₄, filtered, and evaporated to give crude product, which waspurified by column chromatography on silica gel to give 10.7 grams ofliquid product 2.

Compound 3:

Compound 2 (7.72 grams) was dissolved in dry ether under nitrogen. Theflask was cooled in dry ice-acetone cooling bath. LiAlH₄ (1.08 grams)was added. The cooling bath was removed so that the reaction temperaturewas brought to room temperature, at which the reaction was kept for 6hours. The flask was cooled in ice bath. Methanol was added drop-wise toquench the reaction. Brine was added. The organic layer was separated.The aqueous layer was extracted with ether. The combined organic layerswere dried over MgSO₄, filtered through silica gel packed in funnel.After evaporation, compound 3 was obtained in 4.65 grams.

Compound 4:

Compound 3 (4.65 grams) was dissolved in chloroform (100 ml). The flaskwas cooled in ice bath while triphenylphosphine hydrobromide was added.The reaction was stirred at 0° C. for 30 min, then room temperature for14 hours, then refluxed for 3 hours. The reaction mixture wasprecipitated in ether two times to give 8.93 g of product 4.

Compound 6:

Compound 4 (6.71 grams) and compound 5 (5.22 grams) were mixed in dryTHF (100 ml) under nitrogen and cooled in an ice bath. t-BuOK (1M inTHF, 15 ml) was dropped into the mixture via needle. The reaction wasstirred at room temperature overnight and quenched with water. Themixture was neutralized with acetic acid. The product was extracted withmethylene chloride and purified by flash column using a hexane-methylenechloride mixture to give 3.10 grams of compound 6.

Compound 7:

Compound 6 (1.68 grams) was dissolved in dry THF (35 ml) under nitrogen.n-BuLi (2.5M, 1.15 ml) was dropped in via needle at −78° C. The reactionwas kept at −30° C. for 70 min. Then, DMF (0.30 ml) was added via needleat −78° C. After 45 min, the reaction was terminated with ice water. Theproduct was extracted with methylene chloride, dried over MgSO₄,evaporated, and purified by flash column to give compound 7 (1.32grams).

Compound 9:

Compounds 7 (1.264 grams) and 8 (0.767 grams) (see U.S. Pat. No.7,078,542 and references therein for preparation of acceptor compoundsof this type) were mixed in 10 ml ethanol and 5 ml dry THF undernitrogen. The mixture was heated to 45° C. The reaction was monitored byTLC. When compound 7 disappeared from reaction mixture, the solvent wasevaporated on rotary evaporator. The residue was purified by flashcolumn and precipitation of methylene chloride solution in methanol togive 1.03 grams of compound 9 as black powder. U.S. Pat. No. 7,078,542is incorporated by reference herein.

Compound 10:

A total of 5.69 grams of 9 was dissolved in THF (100 ml) under nitrogen.5 ml of 2N HCl was added. The reaction was stirred at room temperatureand monitored by TLC. When the compound 9 disappeared from the reactionmixture, methylene chloride (200 ml) and brine (100 ml) was added. Themixture was neutralized with saturated sodium bicarbonate solution. Theorganic layer was separated, dried over MgSO₄, evaporated, and purifiedby flash column successively to give 5.69 g of compound 10.

Compound 11:

Compound 10 (5.68 grams) was mixed with methylene chloride (50 ml). Theflask was cooled in ice bath. triphenylchlorosilane (6.10 grams) andimadazole (1.40 grams) was added successively. The reaction was stirredand monitored by TLC. After about 30 minutes, compound 10 disappearedfrom the reaction mixture. The salt was filtered out. The product waspurified by flash column and precipitation of methylene chloridesolution in methanol to give 4.10 grams of compound 11.

Other chromophores were prepared using similar reactions and otherstarting materials. For example, when X═C, trityl chloride (Ph₃C—Cl) maybe used in a reaction analogous to that for compound 11.

30 wt % of compound 11 in APC (APC=[biphenyl Acarbonate-co-4,4′-(3,3,5-trimethylcyclo-hexylidene)diphenol carbonate](28), see U.S. Pat. No. 6,750,603) showed very good EO activity ofr₃₃=81 pm/V and very good temporal stability of 92% retention after 20hours at 85° C. Temporal stability tests on a Mach-Zehnder modulatorshowed better than 95% retention of V_(π) after 100 hours at 85° C.

The following synthetic example refers to FIG. 12.

Compound 13:

Compound 12 was dissolved in 70 mL THF while 1N HCl solution (20 mL) wasadded. It was stirred at room temperature for 2 hours. The mixture wasextracted with CH₂Cl₂, washed with NaHCO₃ solution and water, and driedover MgSO₄. After evaporating solvent under reduced pressure, it waspurified by column chromatography with CH₂Cl₂/MeOH (5/0.5) as elutingsolvents. At total of 1.65 g of compound 13 was obtained in 67% yield.

Compound 14:

Compound 13 (0.8 g, 1.07 mmol) and triphenylsilyl chloride (0.945 g, 3.2mmol) were dissolved in 20 mL of CH₂Cl₂. After imidazole (0.22 g, 3.2mmol) was added, the mixture was stirred at room temperature for 1.5hours. It was then filtered and the solvent was removed under reducedpressure. It was purified by column chromatography to give compound 14as a solid.

A 50% compound 14 in amorphous polycarbonate (APC) composite had an r₃₃of 90 pm/V, an optical loss of 0.881 dB/cm, a T_(g) of 140° C., an indexof refraction of 1.6711 at 1.55 microns, and a temporal stability inMach-Zehnder modulators similar to 30% compound 11 in APC as describedabove. A 24% compound 12 in APC composite, in which the aryl groups aresubstituted (replaced) with alkyl groups, had an r₃₃ of 50 pm/V, anoptical loss of 1.44 dB/cm, T_(g) of 140° C., an index of refraction of1.6038 at 1.55, and a much lower temporal stability.

Compound 16:

To a 3-L three necked flask with a stir bar was charged 125 grams oftrimethyl-tetrahydroquinoline (15), and 102 grams of anhydrous potassiumcarbonate (K₂CO₃). Set the flask with a condenser, and an additionalfunnel containing 173.3 grams of p-bromobenzyl bromide in 500 ml dryDMF. The air in flask was flash with nitrogen. 700 ml of dry DMF wasadded to flask. The flask was cooled in ice-water bath. p-bromobenzylbromide was dropped into the flask from the additional funnel attachedto flask while stirring is on. After completion of the addition, thereaction was kept at room temperature for 3 hours. The reaction washeated in 55-60° C. for 14 hours (overnight). The content was allowed tocool down to room temperature, 1 liter of hexanes was added to flask.After stirring for 10 min, the solid was filtered off. The solution wasevaporated on rotary evaporator to dryness. The mixture was dissolved inethyl acetate (1 L), washed with brine two times, dried over MgSO4,filtered, and evaporated. The product was purified by chromatography onsilica gel packed in chromatographic column with hexanes/DCM as mobilephase.

Compound 17:

A 2-l flask equipped with additional funnel and stir bar was chargedwith 66.66 grams of compound 16 from previous step. The flask wasdegassed and filled with dry nitrogen. Anhydrous THF (800 ml) was addedinto flask. The flask was cooled in dry ice-acetone bath. n-BuLi (83 ml)was added from the additional funnel slowly. The reaction was kept at−60° C. for 2.5 hours. In another 3-liter 3-necked flask with 55.7 gramsof triphenylchlorosilane and 200 ml anhydrous THF was prepared and cooedin dry ice-acetone bath. Under stirring, the lithiated solution from thefirst flask was added into the second flask with stirring during 1 hour.The reaction was stirred overnight and was quenched with acetic acidaqueous solution (0.19 mol acetic acid in 300 ml water) and some brinesolution. The organic layer was separated and washed with brine once,dried over MgSO4, filtered, and evaporated to dryness. The product waspurified by silica gel columns using hexanes/DCM as mobile phase.

Compound 18:

147 grams of compound 17 was dissolved in 1000 ml of dry DMF in a 3-Lflask under nitrogen. NBS (51.23 grams) together with 500 ml of DMF wascharged in an additional funnel. The flask was cooled in ice bath andwrapped with aluminum foil to keep light from the reaction. Te NBSsolution was dropped into LM-667 drop wise. The reaction was stirred atroom temperature overnight. DMF was evaporated. The mixture was stirredin Hexanes/ethyl acetate (3:1). The precipitation was filtered off. Thesolution was evaporated. The residual mixture was stirred in methanol.The solid was collected by filtering. Repeat the methanol wash one moretime. The solid was purified by silica gel column chromatography(Hexane/DCM=2:1) and dried under vacuum. Yield of compound 18 is 95%.

Compound 19:

150 grams of compound 18 was charged into a 3-l 3-necked flask with astir bar and additional funnel. The flask was flashed with nitrogen 4times. 1200 ml of anhydrous THF was added via cannulation. The flask wascooled in dry ice-acetone bath. 286 ml of t-BuLi (1.7M) was added dropwise from the additional funnel. After completion of dropping, thefunnel was washed with 25 ml of THF. Then, DMF (anhydrous, 35.81 g) inTHF (200 ml) was added drop wise from the funnel. The cooling bath wasremoved to allow the reaction temperature to reach 0° C. in icebath-water bath. The reaction was quenched with acetic acid aqueoussolution (5:1) until PH value is about 7. Some brine and 500 ml ofhexanes were poured into the mixture. The organic layer was separated,dried over MgSO4, filtered, and evaporated. The product was purified bysilica gel column chromatography using hexane/DCM (3:1 to 1:1) andmethanol wash. Yield of the corresponding aldehyde was 85%. The aldehyde(27.8 grams) was charged into a 1 liter flask with a stir bar. Dry THF(500 ml) was added. The mixture was stirred with some heat to formhomogenous solution. The flask was cooled in ice bath. 1.86 grams ofsodium borohydride (NaBH₄) was added. The flask was flashed withnitrogen. 25 ml of ethanol in 50 ml THF was added from an additionalfunnel during two hours. The reaction was kept stirring at roomtemperature for 18 hours. The reaction is reached full conversion whenthe solution is near clear. When the reaction is finished, brine (50 ml)was added to the reaction and kept stirring for 45 min under high speed.The organic layer was separated, dried over MgSO4, evaporate. Theproduct was purified with flash column chromatography usinghexanes/ethyl acetate. The yield of compound 19 is 95%, which was useddirectly for next step without further characterization.

Compound 20:

A total of 25 grams of compound 19 was dissolved in chloroform (200 ml)in a 1-L flask. The flask was cooled in ice bath. Ph₃PHBr (15.2 g)dissolved in chloroform (200 ml) was dropped into LM-671 during 1 houror so. After stirring at room temperature for 3 hours, the reaction wasreconfigured with Deans-Stark reflux trap to separate water byazeotropic removing chloroform-water distillate for 6 hours. Thereaction was cooled down, evaporated to about 100 ml solution. Thisthick solution was precipitated in dry ethyl ether while stirring is on.The product collected by filtering was dissolved in DCM and precipitatedagain in dry ether. The greenish product was dried over vacuum for aday. Yield of compound 20 is 85%. Proton NMR was collected forcharacterize the compound structure.

Compound 21:

A Total of 0.1 mol of compound 22 in 200 ml dry dichloromethane in aflask was cooled in ice water. Imidazole (0.15 mol) was added. The flaskwas flashed with nitrogen. t-butyldimethylchlorosilane was addeddropwise using syringe. The reaction was stirred for 1 hour. Theprecipitation was filtered out. The solution was washed with brine,dried over magnesium sulfate and evaporated. The product 10 was purifiedby flash chromatography over silica gel. The yield of the correspondingTBDMS ether is 85%. The TBDMS ether (8.37 g) was charged in a flask witha stir bar. The flask was degassed and refilled with nitrogen. n-Buli inhexane was added dropwise from a needle. The reaction was kept between−10° C. and −20° C. for 2 hours. Then DMF was added at −78° C. Thereaction was quenched by acetic acid in water. The organic layer wasseparated, washed with brine, dried over magnesium, and evaporated. Theproduct mixture of two regioisomers was purified by chromatographiccolumn. The yield of compound 21 is 60%.

Compound 23:

To a flask, compound 20 (27.01 g) was charged and degassed. Dry THF wasadded to the flask. n-BuLi in hexane was added dropwise at −20° C. Thereactants were stirred in ice bath for 1 hour. To a second flask,compound 21 (9.511 g) was dissolved in dry THF. The mixture in flask onewas added to the second flask under cooling and stirring. The mixturewas stir 16 hour at room temperature. The reaction was stop by addingwater and some brine. The organic layer was separated, dried overmagnesium sulfate, filtered, and evaporated to dryness. The mixture waspurified by flash chromatography to give the corresponding Wittigcoupling product in a yield of 66%. The coupling product was dissolvedin dry THF in a flask with a stir bar. n-Buli in hexane was added usingsyringe. The reaction was kept at −20° C. for 2 hours. DMF in THF wasadded. The reaction was quenched by brine and acetic acid. The organiclayer was separated, washed with water, dried over magnesium sulfate,filter using Buchner funnel, The mixture was purified by silica gelcolumn chromatography using dichloromethane-hexane mixture as mobilephase to give the corresponding aldehyde. The aldehyde was dissolved inacetone in a flask under nitrogen. 3N HCl aqueous solution was added.The mixture was stirred at room temperature and monitored by TLC. Whenthe reaction reached the end. The mixture was neutralized with saturatedsodium bicarbonate solution. Acetone was evaporated. The product wasextracted with THF and purified further by flash column chromatographyusing THF-DCM as mobile phase to give the corresponding deprotectedalcohol. (23a): The deprotected alcohol in a flask was dissolved in drydichloromethane. Trityl chloride, diisopropylethylamine,4-dimethylaminopyridine was added. The reaction was stirred for 16hours. The precipitation was filtered. The solution was washed withwater, dried with magnesium sulfate, filtered, and evaporated. Theproduct was purified with flash chromatography to give the correspondingtrityl ether. The trityl ether and2-dicyanomethylene-3-cyano-4-methyl-5-trifluoromethyl-5-(4′-phenyl)phenyl-2,5-dihydrofuran(8, FIG. 11) were mixed in ethanol in a flask. The reaction was heatedat 60° C. for 6 hours. The content was cooled to room temperature. Themixture was filtered. The filtrate was purified by column chromatographycombined with methanol or ethanol washed to give chromophore compound23a; (23b) The deprotected alcohol and2-dicyanomethylene-3-cyano-4-methyl-5-trifluoromethyl-5-(4′-phenyl)phenyl-2,5-dihydrofuran(8, FIG. 11) were stirred in ethanol in a flask under nitrogen at 60° C.The reaction was monitored by TLC. After 6 hours, the content was cooledto room temperature. The dark solid was collected by filtration onBuchner funnel. The material was further purified by silica gel columnchromatography and re-crystallization to give a black powder of thechromophore-alcohol with a yield of 60%. The chromophore-alcohol wasdissolved in dry dichloromethane in a flask with a stir bar. Imidazoleand triphenylchlorosilane was added. The reaction was monitored by thinlayer chromatography. After 30 min. the precipitation was filtered. Thesolution was washed with brine, dried over magnesium sulfate, filtered,and evaporated. The compound was further purified by flash columnchromatography, crystallization and wash with hexanes. Yield of compound23b is 70%.

Guest-host EO polymers were prepared with chromophores 23a and 23b withhost polymers 28-30 (FIG. 15). The properties of the EO polymer areshown in Table 1 and Table 2. The number in parentheses behind thematerial reference numbers is the loading % by weight of thechromophore. High Tg of host polymers will lead to higher Tg of the EOcomposites with the same chromophore. In Table 1 and Table 2, compositeswith 29 show higher Tg than 28 composites with the same loading. Thecomposites have similar optical loss and EO coefficient.

TABLE 1 Major EO properties of chromophore 23a. 28-23a 28-23a 29-23a30-23a Property (50%) (55%) (50%) (55%) r₃₃ @ 1.3 μm (pm/V) 92 95 90High leak (corrected) through current Optical Loss @ 1.1-1.2 1.2-1.3 1.31.4 1.55 μm (dB/cm) Chromophore T_(g) 159 159 159 159 (° C.) EO PolymerT_(g) 175 174 199 >202 (° C.) Refractive Index @ 1.7141 1.7300 1.71161.6793 1.5 μm (TM) (poled) (unpoled)

TABLE 2 Major EO properties of chromophore 23b 28-23b 29-23b 29-23b30-23b Property (50%) (50%) (55%) (55%) r₃₃ @ 1.3 μm (pm/ 87-107 — 80-95— V) (corrected) Optical Loss @ 1.2-1.3 1.3 1.3 1.3 1.55 μm (dB/cm)Chromophore T_(g) 157 157 157 157 (° C.) EO Polymer T_(g) 167 199 193 —(° C.) Refractive 1.7339 1.6625 1.7320 1.6926 Index @ 1.5 (unpoled)(unpoled) μm (TM) (poled)

To study the long-term stability of EO polymers, accelerated aging testshave been performed. In these tests the EO polymer films were poledusing Indium Tin Oxide (ITO) as substrate. The poled samples were thensealed in a vacuum environment to avoid the possible oxygen relateddegradation and placed into ovens set at various elevated temperatures.The decay of the EO coefficient r₃₃ was monitored as a function of timeup to 2000 hours. EO polymer composite 28-23a (50%) (Tg 175° C.) wasstudied at 85, 100, and 110° C. (FIG. 16A). At 85° C., r₃₃ remained at94% of the initial r₃₃ after 2000 hours of testing. We also studied28-23b (55%) and 29-23b (55%) at 85° C., 100° C., and 110° C. (FIGS.16B, 16C, 16D, respectively). The Tg of 28 and 29 is respectively 167°C. and 193° C. The graphs FIGS. 16B-D show normalized tested r₃₃ valuesat aging times up to 1800 hours at each temperature. In FIG. 16B, a 29composition showed stability marginally better than the 28 composition.The difference in stability is relatively small because of the largetemperature difference between their respective Tg and the 85° C. testconditions. At 100° C. (FIG. 16C), the 29 system had 2.5% betterstability than the 28 system. At 110° C. (FIG. 16D), the 29 systemshowed 9% better stability than the 28 system. The 29 system was foundto have higher thermal stability than the 28 system at each temperature,with the difference in stability being more marked at higher applicationtemperatures. The effect of the higher host polymer Tg was tosignificantly enhance the composite Tg, and hence to enhance thestability of the measured EO coefficient.

Among different models proposed in the literature we discovered that theone published by Lindsay et al., Polymer 48 (2007), 6605-6616 showedgood consistency between the experimental data and model prediction andis most relevant to our work. We applied the isothermal aging modelJonscher equation:V _(π)(t)/V _(π)(0)=1+(t/τ)^(j)together with Lindsay's hyperbolic tangent approach:ln(τ/τ_(P))=E _(R)(1+tan h[(T _(c) −T)/D])/2RT+E _(P) /RTto model the temperature dependence of the relaxation and to derive theactivation energy of our poled EO polymer systems. In the model, E_(R)and E_(P) are the activation energies of the rigid glassy state and thepliable state, respectively. T_(c) and D are the central temperature andthe width of the transition zone.

The experimental data and the curve fitting results using the Jonscherequation for 28-23a (50%) at three different temperatures 85, 100 and110° C. are shown in FIG. 16E. It can be seen that there is a goodconsistency between our experimental data and the modeling results.Based on the Jonscher equation fitting, we obtained the fittingparameters τ (time constant) and j (the exponent) for all fivetemperatures tested. We then used these τ and j to further extrapolatethe r₃₃ decay (or V_(π) increase) of our EO materials at 25 years. FIG.16B shows the extrapolation of the normalized V_(π) increase in 25 yearsfor 28-23a (50%) at 85, 100 and 110° C. Under 85° C. operation, themodel predicts a V_(π) increase of only 1.14 times. This is asignificant improvement in the long-term stability compared to otherexisting EO polymer systems such as CLD-PI (80° C., FIG. 16B) reportedin Lindsay.

We also show the curve fitting results using the hyperbolic tangentmodel (FIG. 17):ln(τ/τ_(P))=E _(R)(1+tan h[(T _(c) −T)/D])/2RT+E _(P) /RTproposed in Lindsay for EO polymers 28-14 (50%) and 28-23a (50%). Forcomparison purposes, we also re-plotted the curve for CLD-PI (CLD-APEC).The activation energies of 28-14 (50%) (1.09 eV) and 28-23a (1.14 eV)systems are in a similar range. Additionally, switching from 28-14 (50%)(Tg=140° C.) to 28-23a (Tg=174° C.), the transition zone where thematerial stability drastically degrades is pushed significantly towardhigher temperature range (in this case about 20° C. higher).

The Jonscher equation was also used to compare 28-23b (55%) with 29-23b(55%) at 85° C. and 110° C. (FIG. 18). At 85° C., there was nosignificant difference in long term stability. At 110° C., 29-23b (55%)exhibited a 33% increase and 28-23b (55%) showed an 81% increase. Thisindicates that higher Tg polymer systems (e.g., 29) show advantages athigher operation temperature in long term performance.

Mach-Zehnder EO polymer modulators with 23a and 23b with inverted-ribwaveguides were fabricated on 3 inch wafers. The device process flow isillustrated in FIG. 19. Bottom electrodes were sputtered and patterned,then the wafer was treated with an adhesion promoter having thiol andpolar groups, then a layer of bottom clad (LP202C (a thermally curable,crosslinked sol-gel material), or UV15LV) was spun and cured.Inverted-rib waveguides were then fabricated on the bottom clad. After aplasma surface treatment of the bottom clad and the rib waveguides, thecore layer of composites comprised of host polymer and chromophore 23aor 23b was deposited and thermally cured. The top clad LP33ND (athermally curable, crosslinked sol-gel material) was spun and thermalcured after a surface treatment of the core layer. After the entireoptical material stack of the device was built, the poling electrodeswere deposited and patterned, followed by a poling process that wasperformed at a temperature range from 164° C. to 220° C. with a biasvoltage range from 750V to 950V to align the chromophores. The choice ofpoling temperature and voltage depends on the core materials. The polingelectrodes were also designed to serve as working electrodes with anactive length of 2.1 cm. The devices were diced into individual chipsfor testing. The electrode configuration is shown in FIG. 20 and thecross sectional view of one of the polymer modulators is shown in FIG.21.

Optical insertion loss, half-wave voltage (V_(π)), and extinction ratiowere measured. Device V_(π) and insertion loss are tabulated in Table 3.There is no significant difference between 23a and 23b with 28 as hostpolymer. Their insertion losses are also similar. When using 23b with 29as host polymer, the V_(π) is higher.

TABLE 3 V_(π) and Insertion Loss of EO polymer modulators Insertion LossEO Polymer Chip ID Vπ (V) (−dB/cm) 28-23a (50%) V25-25-A 1.28  9.128-23a (55%) V25-8-C 1.09 10.8 28-23b (55%) V25-43-C 1.16  9.8 29-23b(55%) V26-14-B 1.42  8.3

Mach-Zehnder devices using 28-23b (55%) were studied at 85° C. for up to1300-3000 hr (FIG. 22A). The normalized V_(π) of the 28-23b (55%) devicewas found to increase to about 1.02-1.04 times the baseline (initial)V_(π) which corresponds to a 2-4% decrease of r₃₃, which correspondswell to thin film r₃₃ tests. Using a Jonscher model to project 25-yearperformance (FIG. 22B), it is expected that devices made with 28-23b(55%) materials will exhibit an 11% V_(π) increase over 25 years.

Device V_(π) stability was also studied for the higher Tg core 29-23b(55%). After 265 hr at 100 and 110° C., respectively, V_(π) was found toincrease by 1.04 and 1.07 over the initial V_(π). We observed betterstability of devices using a higher Tg core including the higher Tg hostpolymer 29. We further tested 29-23b (55%) up to 150° C. and 170° C. for30 minutes, and found V_(π) increases from the initial V_(π) of 1.12 and1.49 times, respectively. This indicates that short time exposures tohigh elevated temperatures does not ruin the device performance, thusmaking devices fabricated from this material more compatible withelevated temperature processing and/or more immune to failure resultantfrom short term over-temperature conditions.

Integrated Circuit Examples

FIG. 25 is a block diagram of an integrated circuit 101 configured foroptical communication, according to an embodiment 2501. The integratedcircuit 2501 is formed on a substrate 101, and includes electricalcircuitry 104, 105; and an optical polymer stack 110 including opticalcomponents formed on the electrical circuitry 104, 105. An opticaldetector 2508 may be formed at least partially in the electricalcircuitry 104, 105, and may be configured to receive a modulated opticalsignal 2510 from one or more received signal waveguides 2520 formed inthe optical polymer stack 110. The optical detector 2508 may convert theoptical signal 2510 to a first electrical signal 2512. A circuit module2502 formed as a portion of the integrated circuit 101 and theelectrical circuitry 104, 105 may be operatively coupled to the opticaldetector 2508 to receive first data 2504 corresponding to the firstelectrical signal 2512 and responsively output second data 2506. Anelectro-optic modulator 118 including an electro-optic polymer may beformed at least partially in the optical polymer stack 110, beoperatively coupled to the circuit module 2502, and may be configured tomodulate light to output optical data 2524 corresponding to the seconddata 2506.

According to an embodiment, the integrated circuit 101 includeselectrical circuitry 104, 105 including a complex of metal conductors,vias, and dielectric (not shown) and doped semiconductor regions (notshown) formed on a semiconductor substrate. A patterned optical polymerstack 110 can be formed over the surface of the electrical circuitry104, 105. The electrical circuitry 104, 105 includes one or more circuitmodules 2502 configured to receive first data 2504 and output seconddata 2506 responsive to the first data. For example, the one or morecircuit modules 2502 can include one or more or a combination of all orportions of a volatile memory circuit, a memory access circuit, anon-volatile memory (e.g., storage) circuit, a logic circuit, aprocessor core, a multiprocessor core, a communications interface, aGPU, an ASIC, a gate array, and/or a FPGA. For example, if the circuitmodule 2502 is a processor (or multiprocessor), the received first datacan include instructions and data, and the output second data caninclude data that includes a result of the processing. In anotherexample, if the circuit module 2502 is a memory (or memory accesscircuit), then the first data can include a memory address and readcommand and the second data can include the requested data; or the firstdata can include a memory address and write command, and the second datacan include an acknowledgement of the write.

The optical detector 2508 can be operably coupled to the circuit module2502 and configured to receive optical first data 2510 and convert theoptical first data to a first electrical signal 2512 corresponding tothe first data 2404. According to an embodiment, the optical first data2510 and the first electrical signal 2512 can be unidirectional serialdata. An optional input cache and/or router 2514 can include dataparallelization and/or may be configured as a simple (serial or paralleldata) input buffer.

Optionally, the optical detector 2508 may be included in a top-mountedcomponent mounted on top of the optical polymer stack 110. For example,the optical detector may include a PIN diode. According to anotherembodiment, the optical detector may include a third-order nonlinearoptical chromophore configured to undergo a charge separation responsiveto receiving a photon of modulated light. A pair of electrodes mayprovide a DC or AC bias, and light may be sensed by detecting currentflow carried by the separated charges from the third-order nonlinearoptical chromophore.

Optionally, the detector 2508 can be configured to receive a free spaceor Z-axis modulated beam. Optionally the optical first data 2510 can bereceived from an external source (not shown) through an optical fiber2518 coupled to one or more received signal waveguides 2520 formed inthe patterned optical polymer stack 110 via an optical coupler 221.Optionally, the optical coupler 221 may also be formed at least partlyas structures within the patterned optical polymer stack 110.Optionally, the optical coupler 221 can introduce the optical first datato the optical polymer stack 110 and the received signal waveguides 2520through a facet (not shown) formed at the edge of the optical polymerstack 110 or a Z-axis input mirror (shown elsewhere herein) formed inthe optical polymer stack 110.

The second (output) data 2506 from the circuit module 2502 can be outputto an optional output cache and/or router 2522. The optional input cacheand/or router 2522 can include a UART configured to convert paralleldata to serial data. Optionally, the output cache and/or router 2522 caninclude a data multiplexer (see FIG. 2, 210) that can convert relativelyslowly modulated electrical signals into high speed modulation forinsertion onto an optical carrier. Optionally, the output cache and/orrouter 2522 can be configured as a simple (serial or parallel data)output buffer.

A voltage modulation circuit 202 can be configured to receive data fromone or more data sources (for example, a plurality of output cachesand/or routers 2522 operating in parallel) data source and provide amodulated voltage signal to electrodes 116, 136 located proximate to anelectro-optic modulator 118. According to an embodiment, the electrodes116, 136, an electro-optic core, and associated waveguide structures canbe viewed as an electro-optic polymer device 120. Thus, the polymerelectro-optic modulator 118 can be disposed at least partially over theintegrated electrical circuitry 104, 105 and operably coupled to theintegrated electrical circuitry 104, 105 to receive the second data andmodulate light as optical second data. Typically, the voltage modulationcircuit 202 can be configured to modulate a very high speed (e.g. up to40 Gbps or greater) voltage modulated signal onto one or more of theelectrodes 116, 136, and optionally complementary electrodes (not shown)as a substantially equal or inverted voltage modulated signal. Theelectro-optic modulator 118 can take a variety of forms such as a phasemodulator, a Mach-Zehnder modulator, a Michelson interferometer, amicro-ring resonator, a modulated Bragg grating, or other format.

The patterned optical polymer stack 110 disposed at least partially overthe integrated electrical circuitry 104, 105 may include passivewaveguides including a first waveguide 2820 configured to convey theoptical first data 2510 to the optical detector 2508 and a secondwaveguide 226 configured to convey the optical second data 2524 from thepolymer electro-optic modulator 118.

The electro-optic modulator 118 may include an electro-optic polymerconfigured to change its index of refraction responsive to an appliedelectric field. The electro-optic polymer may include a host polymerincluding aryl groups and poled chromophores that include two or morearyl substituents. The aryl substituents on the chromophores may beconfigured to interact with the aryl groups of the host polymer tohinder rotation of the chromophore after poling.

For example, the poled chromophore may include a structure D-π-A inelectronic conjugation, where D, π, and A are defined above. The two ormore aryl substituents may include three aryl groups covalently bound toa substituent center, which is, in turn, covalently bound to thechromophore. As described above, providing this interaction between thehost polymer and chromophores of the electro-optic polymer maysignificantly improve thermal and temporal stability in service, and mayallow for elevated temperature and/or more complex fabrication steps.

The integrated circuit configured for optical communication 2501 mayfurther include a light source (not shown) arranged to providesubstantially continuous output light to the electro-optic modulator 118for modulation by the electro-optic modulator 118. For example, thelight source may includes a vertical cavity laser, a distributedfeedback laser, and/or a vertical cavity laser configured fordistributed feedback. Optionally, the light source (not shown) may beformed at least partially in the integrated electrical circuit 104, 105.One embodiment may be visualized with reference to FIG. 29.Alternatively, the light source (not shown) may be included in atop-mounted component mounted on top of the optical polymer stack 110.One embodiment of this may be visualized with reference to FIG. 30.

The integrated circuit 101 and the integrated electrical circuit 104,105 may also include an input cache or router 2514 operatively coupledto receive the electrical signal 2512 from the optical detector 2508 andprovide the first data 2504 to the integrated circuit module 2502. Forexample, the input signal 2512 a serial signal and the input cache orrouter 2514 may include a serial-to-parallel converter configured toconvert the serial electrical signal 2512 received from the opticaldetector 2508 to parallel data 2504 for use by the integrated circuitmodule 2502. The input cache or router 2514 may optionally include ade-multiplexer configured to split a high speed received first signal2512 to a plurality of lower data rate sets of first data 2504.

The integrated circuit 101 and the integrated electrical circuit 104,105 may also include an output cache or router 2522 configured toreceive the second data 2506 from the circuit module 2502, and convertthe second data 2506 to a second electrical signal corresponding to themodulated optical signal 2524. Optionally, the output cache or router2522 may also include a multiplexer configured to receive a plurality ofsets of second data 2506, and convert the plurality of sets of seconddata 2506 to a high speed second electrical signal (not shown).

A voltage modulation circuit 202 may be configured to receive the secondelectrical signal (not shown) from the output cache or router 2522 andresponsively modulate at least one electrode 116, 136 of theelectro-optic polymer modulator 118 at a voltage selected to cause theelectro-optic polymer modulator 118 to modulate the optical signal 2524to a desired modulation depth.

As indicated above, the optical polymer stack 110 may include a range ofoptical devices. For example, a first optical coupler 221 may beconfigured to couple a first data optical fiber 2518 to the first(received signal) waveguide(s) 2520. A second optical coupler 221 may beconfigured to couple second (modulated optical power) waveguide(s) 226to a second data optical fiber 2528. An optical power optical coupler221 may be configured to couple light from an input optical poweroptical fiber 2526 to transmission optical power waveguides 220 fordelivery to the electro-optic modulator 118. Optionally, the opticalcoupler 221 or Tx optical power waveguide 220 may include a directionalcoupler (not shown) to reduce launching modulation onto what is supposedto be a constant power source 2526.

FIG. 26 is a sectional view of an integrated circuit 2601 configured foroptical communication showing a bottom clad layer 124 configured act asa planarization layer 108, according to another embodiment. Asemiconductor substrate 102 includes a pattern of doped wells 104 on thesurface of the semiconductor substrate 102. A plurality of patternedconductor layers and patterned dielectric layers are disposed over thesurface of the semiconductor substrate 102 to form a circuit layer 105.An optical polymer 124 may form a planarization layer 108 disposed overthe circuit layer 105. A planarized surface 2602 of the optical polymer124 may be a result of spin coating the optical polymer 124 underconditions favorable for leveling, and/or may be a result of chemistrysuch as an in situ crosslinking reaction. The optical polymer formingthe planarization layer 108 may be a portion of an optical polymer stack110 disposed over the circuit layer 105. For example, the opticalpolymer forming the planarization layer 108 may be a bottom polymer clad124.

The plurality of patterned conductor layers and patterned dielectriclayers forming the circuit layer 105 disposed over the surface of thesemiconductor substrate 102 may include one or more exposed conductors2603. The one or more exposed conductors 2603 may be treated to promoteadhesion to the optical polymer forming the planarization layer. Forexample, the treatment of the one or more exposed conductors 2603 mayinclude oxidation to form a metal oxide. An illustrative interaction isshown in FIG. 27A.

The integrated circuit 2601 may include at least one electrical via 112at least partially extending through the optical polymer stack 110 andoperatively coupled to a corresponding at least one location 2604 on theone or more exposed conductors 2603. A top conductor layer 2606 may bedisposed over the optical polymer stack 110 and in electrical continuitywith the at least one electrical via 112. An electrical via 112 may beonly one type of electrical connection between a location 2604 on theconductors 2603 and the top conductor 2606. More generically, theelectrical via 112 may be described as at least one conductor 112 atleast partially extending through the (horizontal) plane of the opticalpolymer stack 110. Accordingly, the arrangement may be described as atleast one conductor 112 at least partially extending through the planeof the optical polymer stack 110 and operatively coupled to acorresponding location 2604 on the one or more exposed conductors 2603.The top conductor layer 2606 may be disposed over the optical polymerstack 110 and in continuity with the at least one conductor 112 at leastpartially extending through the plane of the optical polymer stack 110.This may also place the top conductor 2606 in electrical continuity withthe location 2604. Optionally, the location 2604 may not be an exposedconductor 2603 per se. The location 2604 may correspond to a buriedconductor, a via from a buried conductor, and/or another device such asa plate of a diode (or back-coupled transistor) that is AC coupled toportions of the integrated circuit layer(s) 104, 105.

The at least one conductor 112 may be formed using a variety ofapproaches. For example, as described above, the conductor 112 may be anelectrical via. Alternatively (or additionally), the at least oneconductor 112 may include a wire bond, a conductive bump, and/or ananisotropic conductive region. The top conductor layer 2606 may includea metal layer and/or a conductive polymer.

According to an embodiment, the circuit 2601 may include at least onehigh speed electrode 116, 116 a, 116 b formed as a pattern in the topconductor layer 2606. The high speed electrode 116, 116 a, 116 b may beoperatively coupled to receive a signal from the at least one conductor112 at least partially extending through the plane of the opticalpolymer stack 110.

According to an embodiment, at least a portion of the one or moreexposed conductors 2603 may be configured to form a ground electrode 118parallel to the at least one high speed electrode 116, 116 a, 116 b.

A region 120, 120, 120 b of the optical polymer stack 110 juxtaposed tothe high speed electrode 116, 116 a, 116 b and the ground electrode 118may include a poled region including an electro-optic polymer. Asemiconductor circuit formed from a complex of the doped wells 104 and aportion of the plurality of patterned conductor layers in the circuitlayer 105 may be operable to drive the electrodes 116, 116 a, 116 b, 118with a series of modulated electrical pulses to modulate light passedthrough the poled electro-optic polymer 128, 120, 120 a, and/or 120 b.

According to an embodiment, the integrated circuit or another integratedelectro-optic device may include a velocity-matching layer 2608. Theelectro-optic polymer layer 128 may have a variable optical propagationvelocity of light passed through it, which may, for example, bedependent on an electric field provided by a high speed electrode 116 incooperation with a ground electrode 118. The high-speed electrode 116may be disposed over the top clad 126 and under the velocity-matchinglayer 2608, the high-speed electrode 2608 having an electricalpropagation velocity of electrical pulses passed through it. Thevelocity-matching layer may be configured cause the electricalpropagation velocity through the high speed electrode 116 to approximatethe optical propagation velocity through the electro-optic polymer layer128. A top cladding 126 may be disposed over the electro-optic polymerlayer 128 and below the velocity-matching layer 2608, and be configuredto guide the light to pass substantially through the electro-opticpolymer layer 128. For typical waveguide applications, the top claddinglayer 126 may be configured to convey a portion of light energy that isnominally passed through the electro-optic polymer layer 128. Accordingto an alternative embodiment, the velocity-matching layer 2608 may beformed under the electrodes 116, 116 a, 116 b.

For example, the velocity-matching layer may be configured tosubstantially match the electrical velocity to the optical velocity.Since the optical propagation velocity may be electro-opticallymodulated, for example to provide phase-coding of data and/or to provideamplitude modulation of data on the light signal, the velocity-matchinglayer 2608 may be configured to cause the electrical propagationvelocity through the high speed electrode 116 to approximate an averagevalue of the optical propagation velocity through the electro-opticpolymer 128. To provide the velocity matching, the permittivity of thevelocity-matching layer 2608 may be selected to cause the electricalpropagation velocity through the high speed electrode 116 to approximatethe optical propagation velocity through the electro-optic polymer layer128, and particularly through the electro-optic core 120.

According to an embodiment, the velocity-matching layer includes apolymer made from the monomer:

Polymerization of the velocity-matching layer may beradiation-initiated. For example, the velocity-matching layer mayinclude a photoinitiator.

According to embodiments, an integrated circuit 104, 105 may beconfigured to form a substrate below the electro-optic polymer layer128. As described elsewhere herein, the integrated circuit 104, 105 maybe configured to output the electrical pulses to the high speedelectrode 116. A bottom clad 124 may be disposed between the integratedcircuit 104, 105 and the electro-optic polymer layer 128.

According to an embodiment, the integrated circuit including anelectro-optic polymer stack 2601 may be configured to resist waterinfiltration. In a particular example, one or more upper polymer layers126 and/or 2608 may be configured to protect a water-sensitive area suchas an electro-optic core 120 formed in an electro-optic polymer layer128. In a typical embodiment, the electro-optic core may be formed froma relatively polar molecule. The relatively polar molecule, e.g., asecond order nonlinear chromophore, (aka hyperpolarizable chromophore)may be poled and modulated in a way that may tend to attract water. Oneor more upper polymer layers 126 and/or 208 disposed over theelectro-optic polymer layer 128 may include at least one relativelynon-polar polymer configured to substantially prevent water vapor frommigrating through the one or more upper polymer layers to theelectro-optic polymer layer. As depicted in FIG. 26, the one or moreupper polymer layers may include a top clad 126 and/or avelocity-matching layer 2608. According to an embodiment, the one ormore upper polymer layers 126, 2608 may include a polymer made from atleast the monomer:

A polymer made from the monomer shown above, which may be referred to asLM251 elsewhere herein, was characterized by a water contact anglegreater than 80°. A low surface energy polymer such as one having awater contact angle greater than 80° may tend to exclude water moleculesfrom interstitual locations between crosslinked chains, thussubstantially preventing migration of water from a porous semiconductorpackage and/or an atmosphere contacting the upper surface of the polymerstack 110 through to the electro-optic polymer layer 128. Other polymersmay be substituted to provide this function.

The polymer LM251 that formed layer 2608 was UV cured without anysubstantial elevation in temperature. This may be useful for preventingdepoling of chromophores in the electro-optic polymer 128, which mayhappen during subsequent processing at elevated temperatures near Tg ofthe electro-optic polymer layer 128. Another useful property of LM251was a reduction or elimination of possible chemical attack to exposedelectro-optic polymer 128. The polymer LM251 was found to beparticularly useful as a velocity-matching layer 2608 because itexhibited low RF loss (attenuation of the electrical pulse as ittraveled along the high speed electrode 116, 116 a, 116 b).

According to embodiments, the integrated circuit configured for opticalcommunication 2601 may include one or more upper polymer layersincluding at least one 126 and/or 2608 characterized by a coefficient ofthermal expansion lower than a coefficient of thermal expansion of oneor more layers 124, 128 in the polymer stack 110 disposed between thesemiconductor substrate 102 (and 105, 2603) and the one or more upperpolymer layers 126, 2608.

Table 4 illustrates a relationship between coefficients of thermalexpansion among layers in the integrated circuit 2601 and especially theoptical polymer stack 110 in relationship to the substrate 102, 104, 105and an illustrative conductor 2603 material, according to an embodiment.

TABLE 4 Index No. Name Example Material CTE 2608 Velocity-Matching LM25111.7 126 Top Clad LP33ND 13.4 128 E-O Polymer 29-23b 8.2 124 Bottom CladUV15LV 5.8 118 Bottom Electrode Au 1.4 105, 104, 102 Substrate ~Si ~0.3Where CTE, the coefficient of thermal expansion, is expressed as acoefficient x 10**5° C.**-1. LM 251 is a name for the polymer made fromthe monomer structure shown immediately above, which may be availablefrom Gig-Optix, Inc. LP33ND was disclosed in an earlier patentapplication by the applicant (U.S. patent application Ser. No.12/559,690, entitled LOW REFRACTIVE INDEX HYBRID OPTICAL CLADDING ANDELECTRO-OPTIC DEVICES MADE THEREFORM, filed Sep. 15, 2009, which, to theextent not inconsistent with the disclosure herein, is incorporated byreference. The electro-optic polymer 29-23b is shown above. The bottomclad 124 was made from UV15LV, available from Master Bond, Inc.

The relationship between coefficients of thermal expansion CTE shown inTable 4 may include two or more layers that generally taper in CTE froma substrate 102, 104, 105 CTE to a different CTE of a material that isdisposed elsewhere in the optical polymer stack 110. In other words, theintegrated circuit or other substrate 102, 104, 105 may have a substratecoefficient of thermal expansion (e.g. ˜0.3). A first polymer layer 124disposed over the substrate 102, 104, 105 may have a first coefficientof thermal expansion (5.8). A second polymer layer 128 disposed over thefirst polymer layer 124 may have a second coefficient of thermalexpansion (8.2). The first coefficient of thermal expansion CT1=5.8 mayhave a value between the substrate coefficient of thermal expansionCTS=0.3 and the second coefficient of thermal expansion CT2=8.2.

At least a portion of the gradation in coefficients of thermal expansionmay monotonically change as they progress away from the substrate 102,105, 2603; as is shown in the example optical polymer stack listed inTable 4 and shown as 110 in FIG. 26. The progression of coefficients ofthermal expansion may act as a form of mechanical strain relief that maybe encountered as the IC 102, 104, 105 and/or the optical polymer stack110 thermally cycles in service and/or responsive to temperaturetransients that may be encountered during fabrication. The progressionof coefficients of thermal expansion shown in Table 4 was found toprovide relatively good mechanical robustness. According to anembodiment, providing a gradation in coefficients of thermal expansionCTE may also help to reduce or select polarization dependencies inoptical devices 120, 120 a, 120 b that may arise as a result of stressconcentrations in the optical stack 110.

According to embodiments, the layers 124, 128, 126, and 2608 may beformed by spin coating followed by cooling, polymerization, and/orcross-linking. According to embodiments, the bottom clad 124 may beformed to have a thickness of 2.4 to 2.8 micrometers. The trenchwaveguides 130 may be etched into the bottom clad 124 to a depth of 1.0to 1.2 micrometers, leaving a 1.4 to 1.6 micrometer thickness of bottomclad 124 under the trench waveguides 130. The trench waveguides 130 maybe etched to a width of 3.8 to 4.0 micrometers. The electro-opticpolymer 128 may be formed to have a thickness of 2.15 to 2.2 micrometersover the bottom clad 124 surface, thus having a thickness of 3.15 to 3.4micrometers through the trench waveguide 130. The top clad 126 may beformed to have a thickness of 1.4 to 1.6 micrometers. Thevelocity-matching layer 2608 may be formed to have a thickness of 6 to 8micrometers. The top electrode 116, 116 a, 116 b width may be about 12micrometers.

FIG. 27A is a diagram illustrative of a surface adhesion treatment 2701,according to an embodiment. A surface 2702 of a metal conductor 2603 maybe oxidized to form an oxide 2704 on the surface 2702 of the metalconductor 2603. For example, the metal conductor 2603 may includealuminum, copper, and/or tungsten. An optical polymer such as a bottompolymer clad 124 may be coupled to the metal 2603 via hydrogen bondingor chemical bonding, as indicated. This can improve surface adhesion ofthe optical polymer 124 and thus improve yield, infant mortality, and/orservice life, for example.

FIG. 27B is a diagram illustrative of another surface adhesion treatment2705, according to an embodiment. A surface 2706 of a dielectric 2707may include an oxide such as SiO₂, and/or may include Si₃N₄, SiON,and/or unreacted Si, etc. The surface 2706 may be treated, and/or thebottom clad polymer may be selected such that the surface 2706 undergoeshydrogen bonding or chemical bonding with the bottom clad 124. This canimprove surface adhesion of the optical polymer 124 and thus improveyield, infant mortality, and/or service life.

FIG. 28 is a flowchart showing a method 2801 for making an integratedcircuit configured for optical communication, according to anembodiment. Beginning with step 302, an integrated circuit including atleast one first electrode is provided. For example, providing anintegrated circuit can include receiving a semiconductor wafer includinga plurality of integrated circuits formed thereon. Alternatively,providing an integrated circuit can include fabricating a plurality ofintegrated circuits on a semiconductor wafer. Optional step 2802, step2804, step 2806, optional step 2808, step 2810, step 2818, step 2814,and step 310 together comprise forming an optical polymer stack over theintegrated circuit. At least one second electrode can be applied to theoptical polymer stack and located over at least a portion of anelectro-optic polymer core and a first electrode formed in theintegrated circuit to form an electro-optic polymer device configured toprovide an optical interface for the integrated circuit.

Proceeding to optional step 2802, the surface of at least a portion ofthe integrated circuit surface can be treated to enhance adhesion of theoptical polymer stack. For example, treating at least a portion of thesurface of the integrated circuit can include oxidizing one or moreexposed metal conductors, as shown diagrammatically by FIG. 27A.According to another example, treating at least a portion of the surfaceof the integrated circuit can include depositing a charge on one or moreregions of exposed dielectric, for example using a corona wire,corotron, scorotron, or chemical reaction.

Proceeding to step 2804, a bottom optical clad is applied to the surfaceof the integrated circuit. FIGS. 1 and 2, for example, illustrate anoptical polymer stack that is applied over a dielectric planarizationlayer. Alternatively, as shown in FIG. 26, the bottom optical clad canbe applied over a non-planarized surface of the IC. Step 2804 caninclude applying a bottom cladding polymer over a non-planarized surfaceof the integrated circuit such that the surface of a cured bottompolymer clad is substantially planar. One approach for applying a bottomcladding polymer can includes spin coating the bottom cladding polymer.

Step 2804 can include curing the bottom cladding polymer to form abottom polymer clad. For example, curing the bottom cladding can includecooling a thermoplastic optical polymer to below its glass transitionpoint, Tg1. According to another example, the bottom cladding polymercan include a UV cured polymer or a heat set polymer, and curing thebottom polymer clad can include respectfully providing ultraviolet lightor an elevated temperature. Alternatively, the bottom cladding polymercan be formed by polymerizing liquid phase monomers, such as siloxanesor titoxanes, and curing the bottom polymer clad can include allowing apolymerization reaction to progress, followed by driving off water oranother solvent as a vapor. Curing the bottom polymer clad can include asuccession of two or more curing steps, such as when a thermoplastic orUV-cured polymer is applied over a siloxane-based hybridinorganic-organic polymer. According to embodiments, the bottom clad 124may be formed to have a thickness of 2.4 to 2.8 micrometers.

Proceeding to step 2806, one or more features can be etched in thebottom polymer clad. For example, the one or more features in the bottompolymer clad can include one or more trench waveguides. Such waveguidesare generally formed to guide light to and from polymer optical devices,and also provide light guidance for the electro-optic core of anelectro-optic polymer device. Trench waveguides 130 are illustrated incross-section in FIGS. 1A, 1B, and 26, for example. According toembodiments, the trench waveguides 130 may be etched into the bottomclad 124 to a depth of 1.0 to 1.2 micrometers, leaving a 1.4 to 1.6micrometer thickness of bottom clad 124 under the trench waveguides 130.The trench waveguides 130 may be etched to a width of 3.8 to 4.0micrometers.

Optionally, the optical polymer stack can include features configured tolaunch vertical light propagation from light received from a horizontalwaveguide, or launch light into a horizontal waveguide from receivedvertically propagated light. Typically, such light is referred to as abeam, but it is to be understood that the term beam is not intended tobe limiting. For example, FIG. 30 illustrates an optical polymer stackstructure configured to provide such a transition from horizontal tovertical or from vertical to horizontal propagation.

Referring to step 2806 in view of FIG. 30, etching one or more featuresin the bottom polymer clad can include using a grayscale mask to etch anangled surface 3304 (and a conventional mask to etch the waveguideindicated by the horizontal dashed line). In such a case, proceeding tostep 2808, a mirror material can be patterned onto at least the angledsurface etched in the bottom polymer clad to form a mirror configured tolaunch a beam received from a horizontal waveguide in an upward,substantially vertical direction or to launch a downward beam receivedfrom a substantially vertical direction into a horizontal waveguide.Such a vertical propagation path can correspond to a top-mountedcomponent configured to emit or sense light above the optical polymerstack and vertically aligned to the angled surface, for example.

While FIG. 28 refers to applying metallization, step 2808 is notnecessarily limited to, nor may it even include applying a metal. Forexample, applying a mirror material can include first applying a tielayer configured to promote adhesion between the bottom polymer clad andthe mirror material. The mirror material may include a metal such asaluminum, gold, or silver. Alternatively, the mirror material mayinclude a dielectric stack mirror. According to an embodiment, applyingthe mirror material to at least the angled surface can include applyingthe mirror material to substantially the entire surface of the etchedbottom polymer clad and etching the mirror material off of at least aportion of the surface of the bottom clad not including the angledsurface. Applying the mirror material to at least the angled surface mayalso include applying a seed layer using vacuum metallization andapplying the mirror material to the seed layer using liquid phaseplating. An illustrative seed layer can include a thin layer of vacuumdeposited metal, for example.

Referring again to step 2806, etching one or more features in the bottompolymer clad can include etching substantially through the bottompolymer clad to form a z-axis optical via. For example, FIG. 29 shows az-axis optical via 2904.

Proceeding to step 2810, an electro-optic polymer can be applied overthe etched bottom polymer clad. According to embodiments, theelectro-optic polymer 128 may be formed to have a thickness of 2.15 to2.2 micrometers over the bottom clad 124 surface, thus having athickness of 3.15 to 3.4 micrometers through the trench waveguide 130.According to an embodiment, the electro-optic polymer includes a hostpolymer including at least one aryl group and a chromophore includingtwo or more aryl substituents configured to interact with the at leastone aryl group of the host polymer to hinder rotation of the chromophoreafter poling. Example chromophore structures are shown in FIG. 10.Example host chromophore structures are shown in FIG. 6. Examples ofinteractions between the aryl groups of the host polymer and aryl groupsof the chromophore are shown in FIGS. 14 and 15.

The host polymer can have a relatively high glass transitiontemperature, and the electro-optic polymer can have a glass transitiontemperature higher than the host polymer glass transition temperature.According to an embodiment, the bottom polymer clad can have a firstglass transition temperature Tg1 and the electro-optic polymer can havea second glass transition temperature Tg2 higher than the first glasstransition temperature Tg1 of the bottom polymer clad. For example, thesecond glass transition temperature Tg2 of the electro-optic polymer canbe equal to or greater than 150° C. According to an embodiment, thesecond glass transition temperature Tg2 of the electro-optic polymer isequal to or greater than 175° C.

Step 2810 can include covering substantially the entirety of the polymerbottom clad and filling features etched in the polymer bottom clad. Forexample, filling features etched in the polymer bottom clad can includefiling a z-axis optical via 2904 etched in the polymer bottom clad, asshown in FIG. 29. Similarly, as shown in FIG. 30, applying theelectro-optic polymer can include applying the electro-optic polymerover a mirror surface 3004 formed on a portion of the polymer bottomclad. According to an embodiment, applying the electro-optic polymer caninclude spin coating the electro-optic polymer.

Optionally, after step 2810, the process 2801 can proceed to step 2811,which can include etching one or more features in the electro-opticpolymer. For example, etching one or more features in the electro-opticpolymer can include etching a micro-ring resonator shape in theelectro-optic polymer and/or etching one or more waveguide structures inthe electro-optic polymer. Additionally or alternatively, etching one ormore features in the electro-optic polymer can include using a grayscalemask to etch an angled surface, as shown in FIG. 29 as the surface 2906.In such a case, forming an optical polymer stack can further includeapplying a mirror material to at least the angled surface etched in theelectro-optic polymer to form a mirror 2906 configured to launch a beam122 received from a horizontal waveguide 2906 in a downward,substantially vertical direction or to launch an upward beam 2910received from a substantially vertical direction into a horizontalwaveguide 2906. For example, the angled surface 2906 can be verticallyaligned with a portion of the integrated circuit 2902 configured to emitor sense light.

Applying a mirror material may include first applying a tie layerconfigured to promote adhesion between the electro-optic polymer and themirror material. The mirror material can include a metal such asaluminum, gold, or silver, or alternatively, the mirror material caninclude a dielectric stack mirror. As with step 2808, applying themirror material to at least the angled surface can include applying themirror material to substantially the entire surface of the etchedelectro-optic polymer, and then etching the mirror material off of atleast a portion of the surface of the electro-optic polymer notincluding the angled surface. Applying the mirror material to at leastthe angled surface can also include applying a seed layer using vacuummetallization, and applying the mirror material to the seed layer usingliquid phase plating.

Proceeding to step 2812, a polymer cladding may be applied over theelectro-optic polymer to form a top polymer clad 126. For example,applying a polymer cladding may include spin coating the polymercladding. According to an embodiment, the top clad 126 may be formed tohave a thickness of 1.4 to 1.6 micrometers. According to an embodiment,the top polymer clad can have a third glass transition temperature Tg3that is lower than a second glass transition temperature Tg2 of theelectro-optic polymer, or the top polymer clad can have a third glasstransition temperature Tg3 that is higher than a second glass transitiontemperature Tg2 of the electro-optic polymer.

Proceeding to step 2814, at least one electrode may be applied or formedover the top polymer clad. For example, the at least one electrodeapplied over the top polymer clad may include a temporary electrode usedfor poling, in which case the temporary electrode is removed afterpoling. If the electrode(s) applied in step 2814 is (are) polingelectrode(s), then a permanent electrode can be applied after the polingelectrode is removed. Alternatively, the applied at least one electrodemay include a permanent electrode used for both poling and formodulation once the circuit is in use. According to an embodiment, thetop electrode 116, 116 a, 116 b width may be about 12 micrometers.

Proceeding to step 310, at least portions of the electro-optic polymerare poled and cured. For example, step 310 can include 1) raising thetemperature of the integrated circuit and the optical polymer stack tonear a glass transition temperature Tg2 of the electro-optic polymer; 2)applying a poling voltage across the top polymer clad, the electro-opticpolymer, and the bottom polymer clad to induce alignment of molecules ofthe polar chromophore in the electro-optic polymer; and 3) lowering thetemperature of the integrated circuit and the optical polymer stack tobelow the glass transition temperature Tg2 of the electro-optic polymer.“Near the glass transition temperature Tg2 of the electro-optic polymer”can mean within 10° C. of the glass transition temperature Tg2.

According to an embodiment, the glass transition temperature T_(g2) ofthe electro-optic polymer can be equal to or greater than 150° C. Forexample, the glass transition temperature Tg2 of the electro-opticpolymer can be about 167° C. as shown above for the electro-opticpolymer 28-23b at 50% loading. According to another example, the glasstransition temperature Tg2 of the electro-optic polymer can be about175° C., as shown above for the electro-optic polymer 28-23a. Accordingto another example, the glass transition temperature Tg2 of theelectro-optic polymer can be about 199° C., as shown above for theelectro-optic polymers 29-23a and 29-23b. Raising the temperature of theintegrated circuit and the optical polymer stack to near a glasstransition temperature Tg2 of the electro-optic polymer can includeraising the temperature to between 164° C. and 220° C., for example.

The poling voltage applied across the top polymer clad, theelectro-optic polymer, and the bottom polymer clad can be between 750Vand 950V, for example. Applying the poling voltage can include holdingthe at least one electrode and other circuit nodes in the integratedcircuit at a first potential, and holding an electrode above the opticalpolymer stack at a second potential separated from the first potentialby the poling voltage. Holding circuit nodes at the bottom electrodepoling voltage can help reduce yield loss caused by dielectric breakdownthrough dielectric and/or components of the integrated circuit.

According to an embodiment the first potential can be substantially atground, and the second potential can be between about 750V and 950V.Holding the at least one electrode and other circuit nodes at a firstpotential includes contacting at least one pad on the integrated circuitwith a poling probe that penetrates the optical polymer stack.

Optionally, before or after the poling step 310, the process 2801 mayinclude a step (not shown) where a velocity-matching layer 2608 may beformed to have a thickness of 6 to 8 micrometers. As described above,the velocity matching layer 2608 may help to synchronize electrical andlight propagation speeds.

After proceeding through step 310, the process 2801 may optionallyproceed to step 2816, where at least one top-mounted component may bepicked-and-placed over the optical polymer stack. For example, FIG. 30shows a top-mounted component 3002. The top-mounted component 3002 maybe configured to emit or sense light on top of the optical polymerstack. For example, the top-mounted component 3002 may include adistributed feedback laser configured to output a CW wavelength.Alternatively, the top-mounted component may include a photodiode orother optical detector configured convert an optical signal into anelectrical signal.

After step 310 and/or optional step 2816, the process 2801 may proceedto step 2818. Step 2818 typically includes testing the integratedcircuit and optical polymer stack. Optionally, the optical polymer stackcan be reworked by stripping it off the wafer and making it again, iftesting shows the optical polymer stack to be defective. Testing can bedone prior to or after dicing a semiconductor wafer to singulate theintegrated circuit. The integrated circuit and optical polymer stack canbe packaged after singulation. Generally, packaging can includeproviding optical fiber pigtails that couple to optical couplers formedin, on, or adjacent to the optical polymer stack. Packaging cangenerally also include providing electrical contacts.

According to some embodiments, an optical device can be formed as anintegrated circuit 104, 105 portion. For example a vertical cavity laser(VCSL) can emit a pattern of light in a substantially vertical axis(z-axis). In another example, an integrated light detector can exhibithighest sensitivity along a substantially vertical axis. FIG. 29 is asectional view of an optical stack structure 110 including an embodiment2901 including a coupling between a horizontal waveguide 2908 and az-axis launch to or from a device 2902 formed at the surface of the IC101. According to embodiments (that may, for example, be limited toelliptically polarized or nonpolarized light) light propagation pathscan often be viewed as being independent of propagation direction.Accordingly, the device 2902 can be a light detecting or a lightemitting device.

Optionally, a via 2904 can be formed through the bottom clad 124 andoptionally through dielectric portions of the circuit layer 105. Anelectro-optic polymer layer 128 can be applied to the wafer such thatthe electro-optic polymer fills the via 2904. Placing the electro-opticpolymer in contact or nearly in contact (for example, separated by anetch stop) with the surface of the IC 101 can reduce or eliminate losssurfaces, and thus transmit a larger portion of power in a light beam.Optionally, the via 2904 may be omitted and a vertical beam canpropagate through dielectric in the circuit layer 105 and/or the bottomclad 124.

A turning mirror 2906 is configured to reflect a horizontal beam 122received through a horizontal waveguide 2908 to a z-axis beam 2910.Alternatively, the turning mirror 2906 can reflect a z-axis beam 2910 toform a horizontal beam 122 guided substantially through theelectro-optic polymer 128 by the horizontal waveguide 2908. The turningmirror surface can be formed by etching a pattern formed by a grayscalemask such that the amount of etching depth varies substantially linearlyalong the width of the turning mirror 2906. Alternatively, the turningmirror surface can be formed by off-axis dry etching, although mirrorsurface quality may suffer with this approach. After etching away aportion of the electro-optic polymer 128 and optionally a portion of thebottom clad 124, the etched surface may be coated or plated to form amirror surface at coincident with the angled etched facet. The turningmirror 2906 can be a metal mirror (thus representing a portion of anintermediate patterned metalized layer, described in FIG. 28) or can bemade by quarter-wavelength stacked dielectric or electro-optic layers. Atop clad 126 can fill in the volume over and behind the mirror 2906 aswell as form a top clad 126 configured to guide light along thehorizontal waveguide 2908.

FIG. 30 is a sectional view of another optical stack structure 3001including a coupling between a horizontal waveguide 2908 and a z-axislaunch to or from a top-mounted component 3002, according to anembodiment. For example, the top-mounted component 2002 can include anoptical coupler, an optical detector, or a laser light source.Alternatively, the top-mounted component 2002 can represent acorresponding location on a second, inverted integrated circuit andoptical stack, which can either be in contact with the surface of theoptical stack shown, or can be located a longer distance away withfree-space propagation between the two, non-contacting optical stacks.Similarly, the top-mounted component can represent an optical couplerlocated a distance away, for example on an integrated circuit package, amulti-chip module, or a printed circuit board, such as for providing anoptical interface to an integrated circuit that is mounted via a ballgrid array (BGA) or other “flip-chip” technology.

The descriptions and figures presented herein are necessarily simplifiedto foster ease of understanding. While various aspects and embodimentshave been disclosed herein, other aspects and embodiments arecontemplated. The various aspects and embodiments disclosed herein arefor purposes of illustration and are not intended to be limiting, withthe true scope and spirit being indicated by the following claims.

What is claimed is:
 1. An integrated circuit configured for opticalcommunication, comprising: an integrated circuit including at least oneconductor layer; and an optical polymer stack disposed on the integratedcircuit and the at least one conductor layer, the optical polymer stackincluding at least one electro-optic core; wherein the integratedcircuit includes circuitry configured to modulate data onto at least oneoptical wavelength operatively coupled to the at least one electro-opticcore; and wherein the electro-optic core includes a poled electro-opticpolymer comprising: a host polymer including at least one aryl group;and a poled chromophore including two or more aryl substituentsconfigured to interact with the at least one aryl group of the hostpolymer to hinder rotation of the chromophore after poling.
 2. Anintegrated circuit configured for optical communication, comprising: anintegrated circuit including at least one conductor layer; and anoptical polymer stack disposed on the integrated circuit and the atleast one conductor layer, the optical polymer stack including at leastone electro-optic core; wherein the integrated circuit includescircuitry configured to modulate data onto at least one opticalwavelength operatively coupled to the at least one electro-optic core;and wherein the electro-optic core includes a poled electro-opticpolymer comprising: a host polymer including at least one aryl group;and a poled chromophore including two or more aryl substituentsconfigured to interact with the at least one aryl group of the hostpolymer to hinder rotation of the chromophore after poling, wherein thepoled chromophore includes a structure D-π-A in electronic conjugation;wherein the two or more aryl substituents include three aryl groupscovalently bound to a substituent center; and wherein: D is an electrondonor group; π is a pi-orbital electron conjugated bridge; and A is anelectron acceptor group configured to receive electron density from Dvia π.
 3. The integrated circuit configured for optical communication ofclaim 1, wherein each of the two or more aryl substituents include thestructure:

wherein: X is the substituent center; Ar¹, Ar² and Ar³ are the arylgroups; L is a covalent linker attached to D, p, or A; X is C, Si, N,Sn, S, S(O), SO2, P(O), aromatic ring, or P; Ar¹, Ar² and Ar³ eachindependently include a substituted or un-substituted phenyl ring, asubstituted or un-substituted benzyl ring, a substituted orun-substituted naphthyl ring, a substituted or un-substituted biphenylgroup, a substituted or un-substituted pyridyl ring, a substituted orun-substituted bipyridyl group, a substituted or un-substitutedthiophene ring, a substituted or un-substituted benzothiophenene ring, asubstituted or un-substituted imidazole ring, a substituted orun-substituted thiozale ring, substituted or un-substitutedthienothiophene group, substituted or un-substituted a substituted orun-substituted quinoline group, or a substituted or un-substitutedanthracenyl group; and L includes the structure:

wherein: R¹ is independently at each occurrence an H, an alkyl group, ora halogen; Y¹ is —C(R¹)₂—, O, S, —N(R¹)—, —N(R¹)C(O)—, —C(O)₂—, —C₆H₆—,or —OC₆H₆—, or thiophenyl; n is 0-6; and m is 1-3.
 4. The integratedcircuit configured for optical communication of claim 1, wherein theconductor layer includes a first electrode; and wherein theelectro-optic polymer stack includes an electro-optic polymer layerdisposed over the first electrode; and wherein the semiconductorintegrated circuit is configured to drive the first electrode with avoltage signal selected to drive the electro-optic polymer layer.
 5. Theintegrated circuit configured for optical communication of claim 4,wherein the electro-optic polymer layer includes the electro-optic core.6. The integrated circuit configured for optical communication of claim4, wherein the first electrode is driven with a toggled voltage to drivethe electro-optic polymer layer.
 7. The integrated circuit configuredfor optical communication of claim 4, wherein the first electrode isdriven with a ground voltage to drive the electro-optic polymer layer.8. The integrated circuit configured for optical communication of claim1, further comprising: a planarization layer adjacent to the at leastone conductor layer and a dielectric layer disposed between patternedconductors in the at least one conductor layer.
 9. The integratedcircuit configured for optical communication of claim 1, wherein the atleast one conductor layer includes a first electrode; wherein theintegrated circuit includes circuitry configured to drive a travelingwave electrical pulse along the first electrode; and wherein theelectro-optic core is parallel to the first electrode and configured toreceive the traveling wave electrical pulse from the first electrode.10. The integrated circuit configured for optical communication of claim9, wherein the traveling wave electrical pulse travels at a firstpropagation rate substantially corresponding to a second propagationrate of light traveling through the electro-optic core.
 11. Theintegrated circuit configured for optical communication of claim 1,wherein the optical polymer stack includes a guiding structure includingat least one selected from the group consisting of a trench waveguide, arib waveguide, a quasi-trench waveguide, a quasi-rib waveguide, and aside clad.
 12. The integrated circuit configured for opticalcommunication of claim 1, further comprising: a second electrodedisposed on top of the optical polymer stack, the second electrode beingoperatively coupled to the semiconductor integrated circuit.
 13. Theintegrated circuit configured for optical communication of claim 12,wherein the at least one conductor layer of the integrated circuitincludes a first electrode; wherein the first electrode and the secondelectrode are coupled to receive electrical signals from thesemiconductor integrated circuit and responsively cooperate to providean electric field across the electro-optic core.
 14. The integratedcircuit configured for optical communication of claim 13, wherein thesemiconductor integrated circuit is configured to provide a toggledsignal to the first electrode.
 15. The integrated circuit configured foroptical communication of claim 13, wherein the semiconductor integratedcircuit is configured to provide a toggled signal to the secondelectrode.
 16. The integrated circuit configured for opticalcommunication of claim 13, further comprising at least a secondconductor layer below the first electrode, the second conductor layerbeing configured to form a buried electrode operatively coupled to thefirst electrode.
 17. The integrated circuit configured for opticalcommunication of claim 16, wherein the buried electrode is separatedfrom the first electrode by a dielectric layer.
 18. The integratedcircuit configured for optical communication of claim 17, wherein theburied electrode is electrically coupled to the first electrode by aplurality of vias through the dielectric layer.
 19. The integratedcircuit configured for optical communication of claim 13, wherein theintegrated circuit includes a driver circuit coupled to drive the firstand second electrodes.
 20. The integrated circuit configured for opticalcommunication of claim 19, wherein the integrated circuit includes amultiplexer configured to receive a plurality of input electricalsignals, multiplex the plurality of input electrical signals, and outputat least one multiplexed signal to the driver circuit.
 21. Theintegrated circuit configured for optical communication of claim 19,wherein the integrated circuit includes a matching circuit coupled toreceive signals from at least one of the first and second electrodes.22. The integrated circuit configured for optical communication of claim1, wherein the at least one conductor layer includes a first electrodeand a poling coupling pad electrically coupled to the first electrode.23. The integrated circuit configured for optical communication of claim1, wherein the semiconductor integrated circuit includes an integratedcircuit formed using at least one process selected from the groupconsisting of MOS, NMOS, PMOS, and CMOS.
 24. The integrated circuitconfigured for optical communication of claim 1, wherein the integratedcircuit includes a plurality of doped semiconductor devices coupled todrive at least one electrode formed in the at least one conductor layer.25. The integrated circuit configured for optical communication of claim1, wherein the at least one conductor layer includes a plurality ofsubstantially planar discontinuous structures including at least onepoling voltage coupling pad and at least one optical channel drivingelectrode that can be held at least temporarily in electrical continuitywith at least one poling voltage coupling pad.
 26. The integratedcircuit configured for optical communication of claim 25, wherein thepoling voltage coupling pad is configured to receive a first polingpotential; and wherein the top of the optical polymer stack isconfigured to receive a second poling potential.
 27. The integratedcircuit configured for optical communication of claim 1, wherein: the atleast one electro-optic core forms a portion of an electro-optic device;and wherein the integrated circuit further comprises: a feedback circuitconfigured to receive a second light signal and responsively controlmodulation of a first light signal by the electro-optic device.
 28. Theintegrated circuit configured for optical communication of claim 27,wherein the electro-optic device is configured to modulate the firstlight signal to produce the second light signal.
 29. The integratedcircuit configured for optical communication of claim 1, furthercomprising: an optical detector included in or operatively coupled tothe integrated circuit and configured to receive input optical data fromone or more external sources; and wherein the at least one electro-opticcore forms a portion of an electro-optic device configured to be drivenby the integrated circuit to output optical data to one or more externaldestinations.
 30. The integrated circuit configured for opticalcommunication of claim 29, wherein the optical detector is a portion ofthe integrated circuit.
 31. The integrated circuit configured foroptical communication of claim 29, wherein the optical detector ismounted on top of the optical polymer stack.
 32. The integrated circuitconfigured for optical communication of claim 29, wherein the opticalpolymer stack further comprises: one or more passive waveguidesconfigured to convey the input optical data to the optical detector. 33.The integrated circuit configured for optical communication of claim 1,wherein the at least one electro-optic core is a portion of an opticalphase modulator.
 34. The integrated circuit configured for opticalcommunication of claim 1, wherein the at least one electro-optic core isa portion of a Mach-Zehnder modulator.
 35. The integrated circuitconfigured for optical communication of claim 1, wherein the at leastone electro-optic core is a portion of a micro-ring modulator.
 36. Theintegrated circuit configured for optical communication of claim 1,further comprising: an optical detector configured to receive amodulated optical signal and convert the optical signal to a firstelectrical signal; and a circuit module operatively coupled to theoptical detector and the circuitry configured to modulate data onto atleast one optical wavelength, the circuit module formed as a portion ofthe integrated circuit configured to receive first data corresponding tothe first electrical signal and responsively output second data to thecircuitry configured to modulate data onto the at least one opticalwavelength; wherein the electro-optic core is formed as an electro-opticmodulator configured to cooperate with the circuitry configured tomodulate data onto at least one optical wavelength and configured tooutput a modulated light signal corresponding to the second data on theat least one optical wavelength.
 37. The integrated circuit configuredfor optical communication of claim 1, wherein the integrated circuitfurther comprises: a semiconductor substrate; a pattern of doped wellson the surface of the semiconductor substrate; and a plurality ofpatterned conductor layers and patterned dielectric layers disposed overthe surface of the semiconductor substrate and forming a circuit layer;wherein the optical polymer stack further comprises: an optical polymerforming a planarization layer disposed over the circuit layer.
 38. Theintegrated circuit configured for optical communication of claim 1,wherein the electro-optic core has a variable optical propagationvelocity of light passed therethrough; wherein the optical polymer stackincludes a velocity-matching layer disposed over the electro-optic core;further comprising: a high-speed electrode disposed over thevelocity-matching layer operatively coupled to the integrated circuit,the high-speed electrode having an electrical propagation velocity ofelectrical pulses passed therethrough; wherein the velocity-matchinglayer is configured cause the electrical propagation velocity throughthe high speed electrode to approximate the optical propagation velocitythrough the electro-optic core.
 39. The integrated circuit configuredfor optical communication of claim 1, wherein the electro-optic coreincludes one or more polar species; and wherein the optical polymerstack includes one or more upper polymer layers disposed over theelectro-optic core; wherein the one or more upper polymer layersincludes at least one relatively non-polar polymer configured tosubstantially prevent water vapor from migrating through the one or moreupper polymer layers to the electro-optic core.
 40. The integratedcircuit configured for optical communication of claim 1, wherein theintegrated circuit has a substrate coefficient of thermal expansion; andwherein the optical polymer stack further comprises: a first polymerlayer having a first coefficient of thermal expansion disposed over theintegrated circuit; and a second polymer layer having a secondcoefficient of thermal expansion, disposed over the first polymer layer;wherein the first coefficient of thermal expansion has a value betweenthe substrate coefficient of thermal expansion and the secondcoefficient of thermal expansion.
 41. The integrated circuit configuredfor optical communication of claim 40, wherein the first polymer layeris a bottom clad and the second polymer layer is the electro-optic core.